Search engines can't see and can't click, so there's a big overlap between making sites accessible and making sites perform well in search engines. Social media also uses several features that improve accessibility.
This table shows the relationships between WCAG 2 Accessibility Checkpoints, search engine optimization and social media. The priority levels from WCAG have been used for SEO and social media: A is most important, AAA is least important.
| Accessibility | SEO | Social | WCAG 2 checkpoint | |
|---|---|---|---|---|
| Text Alternatives | A | A | 1.1.1 | |
| Video Transcripts | A | A | 1.2.1 | |
| CSS Content | A | A | 1.3.1 | |
| Images of Text | AA | A | 1.4.5 | |
| Page Titles | A | A | A | 2.4.2 |
| Link Text | A | AA | 2.4.4 | |
| Multiple Ways to Pages | AA | A | 2.4.5 | |
| Headings and Labels | AA | AAA | 2.4.6 | |
| Link Purpose | AAA | A | 2.4.9 | |
| Section Headings | AAA | AAA | 2.4.10 | |
| Language of Page | A | A | 3.1.1 | |
| Parsing | A | AA | AA | 4.1.1 |
| Meta Descriptions | A | A |
Search engines and blind people can't see images, so they need text alternatives to describe important images.
<img src="red-sands-resort.jpg" alt="Red Sands Resort is perched on the slopes of Olympus Mons, overlooking the Tharsis plain, 200 million km from the nearest beach" />
ALT text is used in image search, and also used as anchor text when a link surrounds the image. Anchor text helps to determine the topic of the target page, with offsite anchor text given more weight because it's harder to manufacture links on lots of different sites.
Currently social media sites like Pinterest and Facebook don't capture ALT text when images are shared. Pinterest uses the image description typed when the user pins the image. Facebook sets empty ALT text for thumbnail images of shared pages - even if the shared page contains ALT text for the thumbnail image.
Screen readers read out ALT text in place of images. Images which are essential to understanding or functionality must have ALT text:
<a href="https://www.powermapper.com/"><img src="logo.png" alt="Home Page"></a><input type="image" src="submit.png" alt="Book Mars Trip" /><img src="radiation-hazard.png" alt="Danger - radiation hazard beyond airlock" />
<img src="transparent-spacer.png" alt="" /> <img src="images/stock-photos/grinning-businessmen-shaking-hands.png" alt="" /> Warning: This is one place where SEO guidelines and accessibility guidelines part company. Both Google and Bing recommend all images should have ALT text (which makes them easier to index for image search) but this harms accessibility by adding noise to the page for purely decorative images.
Just like images, search engines and blind people can't see video, so need text alternatives. Sometimes optimizing a site for SEO has the side effect of producing very accessible content. A good example is SeoMoz (a producer of SEO tools) who add transcripts to all their videos to help with ranking. This has the side effect of making the video accessible to the deaf.
The CSS content property allows text to be inserted dynamically - a typical usage is adding a page number to the footer of printed documents.
div.caption { content: "Red Sands Hotel"; }
Text inserted using the CSS content property is invisible to a search engine. Some low vision and dyslexic users turn off stylesheets, or apply their own CSS stylesheet. This allows users to set combinations of text color, background color and font style that work best for their particular abilities. For these users content inserted via CSS is never displayed.
Images of text cannot be seen by search engines or screen readers. It's nearly always better to use text styled with CSS. The main exceptions are:
The title tag is crucial for SEO and social media, and very important for accessibility. Title tags identify a page to the user - they appear in lots of different places: search results; browser tab titles, bookmarks and Facebook shares.
<title>Magnificent vacations on Mars - Travel - Destination Travel</title>
The title is the most important item on a page for a search engine, and should be written for users. A good rule of thumb is to write titles the same way as a quality newspaper writes headlines. An informative title like "Good title tags boost business results" gets clicked on a lot more often than a keyword stuffed title like "Good title tags, best title tags, cheap title tags, title tag advice".
Words at the start of the title are read more often during a quick scan of the results, so carry more ranking weight with the search engine. For this reason, don't put the site name at the start of page titles (other than on the home page).
Don't use the same title tag on every page on your site - because the title has a huge influence on ranking this greatly reduces the number of keywords your site will rank well for.
For more information see Title Tag Optimization for Usability and SEO
Facebook and Digg show the page title for shared links, along with any meta description.
The title is the first thing read when a page loads, and is very important for letting the user know where they are. Having identical titles on every page is very confusing.
<a href="things-to-do.htm">Things to do on Mars</a>
Search engines use the underlined link text (called anchor text in the SEO world) as a vote on the topic of the target page. If enough anchor text points at a particular page, searching for that anchor text returns the page even if the text doesn't exist on the target page. This has been exploited in the past by Google Bombing.
Three main screen reader interactions use link text:
In first two cases the links need to make sense out of context by clearly identifying link purpose. In particular, labeling all your links "Click Here" or "Read More" renders the links useless to screen reader users unless they read sequentially.
A single navigation mechanism (such as a navigation bar) may block or slow down some users with disabilities. Providing multiple navigation methods (navigation menus, search and a site map) helps disabled users avoid these blocks.
Blind and low vision users may find it quicker to navigate using site search, or search for text in a site map, rather than tabbing through a navigation menus in set of linked pages.
Search engines count internal and external links to a page to work out how important the page is. Providing multiple internal links to a page increases the chances that page will be indexed.
<h1>Magnificent vacations on Mars</h1> <h2>Prices for vacations on Mars</h2> <h3>Budget Vacations</h2> <h3>Luxury Vacations</h2> <h2>Related: vacations on Venus</h2>
Headings help the search engine understand the topic of a page. The headings on this blog post help indicate the page is about screen readers, search engines and social media.
Many screen reader users read out a list of headings as soon as the arrive at a page to get a quick overview of a page - this is equivalent to a sighted user quickly scanning the page before deciding to hit the back button. They're also used to quickly navigate to the part of page the user is interested in. Without headings the user has to laboriously read the page from the top.
The HTML tag at the top of each page should identify the language the page is written in:
<html lang="en">
Search engines can guess the language of a pages, but sometimes guess wrongly (especially on multi-lingual sites). Without this attribute a French language page on a Canadian site may appear in English search results instead of French search results (or more likely not appear at all).
This attribute is used when selecting a voice to read out the page in. Without this attribute a French language page can be pronounced like English in a screen reader (which is unintelligible to a French speaker).
Search engines parse pages using "tag soup" algorithms that are very forgiving of errors. Relying on this can cause problems, because error handling wasn't standardized until HTML5. This means an unclosed tag may be handled differently by different search engines. Particular problems include:
Facebook and Digg displays page title and meta description when a link is shared, so Facebook needs to parse the page in the same way as a search engine to extract this information. The same problems with malformed tags apply.
Screen readers rely on the host browser parsing pages before interacting with the browser DOM via accessibility APIs. The way browsers handle malformed code sometimes changes between browser releases. There were parsing changes between Internet Explorer 7 and 8 as well as parsing changes between Firefox 3 and 4.
Meta descriptions provide a short description of a page, and are displayed below page titles in search results and shared links in Facebook.
<meta name="description" content="With nearly every corner of Earth developed, more of today's elite tourists are boarding rocket ships to vacation in hundreds of off-planet hotels, resorts and spas that are putting a new spin on 'out-of-this-world' luxury" />
The meta description usually appears below the title, with keywords from the user's search phrase in bold.
The description should give users a reason to click - a description that says "Under construction" is unlikely to get many clicks. Use language that people actually use in searches rather than corporate jargon, because this means more text is bolded to attract attention which increases the number of clicks.
Facebook and Digg show the page meta description just below the page title for shared links.
Not used directly by screen readers, but will be read out as part of search results pages returned by Google and Bing.
Optimizing a site for search engines and social media usually makes it more accessible. Making a site more accessible optimizes it for search engines and social media. Do both!
A robots.txt file is a digital "Keep Out" sign, designed to keep web crawlers out of certain parts of a web site.
The most common use of robots.txt is preventing pages appearing in search engines like Google. Common examples are:
Scanning either of these types of pages shouldn't cause problems when SortSite or PowerMapper ignores the robots.txt option. You probably always want to check these pages for broken links and accessibility issues.
Robots.txt is also sometimes used to block robots from part of the sites where robots fetching lots of pages can cause problems (e.g. a set of pages that run slow database queries). This is much less common, since aggressive bad robots (e.g email address spambots) ignore robots.txt anyway, so blocking doesn't usually help.
Contact the web site's administrator or webmaster to determine the reason a site has blocked access via robots.txt.
Adding the following entries to the robots.txt file will bypass any blocks intended for other web crawlers:
User-agent: PowerMapper
Allow: /The PowerMapper user agent in robots.txt is understood by all PowerMapper products.
See Also:Pages blocked by robots.txt
Applies To: all versions
Last Reviewed: November 14, 2020
If too few pages are scanned there are several possible causes:
The crawler only visits pages on the same domain as the home page, so pages on a different domain do not appear on the map. To add other domains to the same report or sitemap, select the Options command from the View menu, and add the additional domain names to the Additional Domains box in the Links tab.
Some pages were blocked by the Robot Exclusion Standard (robots.txt) or explicitly blocked in the Blocks tab on theOptions window.
To find out which links are blocked by robots.txt for a site, https://www.google.com for example, open the address https://www.google.com/robots.txt. If you get a 404 Not Found message then no links are blocked, if you get a text file back this lists which links are blocked.
In the desktop versions, you can ignore the Robot Exclusion Standard by selecting the Options command from the View menu and unchecking Obey Robots.txt
Adding the following entries to the robots.txt file will bypass any blocks intended for other web crawlers:
User-agent: PowerMapper
Allow: /The PowerMapper user agent in robots.txt is understood by all PowerMapper products.
See Also:What is robots.txt
Applies To: PowerMapper 3.0 and SortSite 3.0 or later
Last Reviewed: November 14, 2020
OnDemand Suite includes cloud versions of the following applications:
One click is all it takes to analyze an entire web site. Each page is checked against more than 1200standards based checkpoints.
PowerMapper draws maps in a range of useful and attractive styles using thumbnails of each page. You can also export a Google XML sitemap, or an Excel CSV.
Problems like broken links, spelling errors and usability problems drive visitors away from your site. Search engine issues stop visitors before they arrive. Find and fix website problems before your customers or executives find them.
Manual testing effort is proportional to the number of pages, so costs quickly add up, even on small sites:
SortSite tests the same site in under 5 minutes for a small fraction of the cost of testing everything manually. This lets teams focus manual testing on areas that require human judgement.
Generating this kind of map of an existing site should be the first step anyone takes when redesigning a site. Steve Krug, Author "Don't Make Me Think"
This simple test ... gives much more useful data than just a screenshot. The "SortSite" test checks accessibility, broken links, browser code compatibility, search engine optimization and other usability issues...
practicalecommerce.com
Our products are used in more than 50 countries by some of the world's largest organizations. Over 30% of the Fortune 100 use our products.
Example reports produced by the OnDemand Suite, and free trials.
Get in-depth technical information about OnDemand features, benefits, and capabilities.
More documentation including datasheets, white papers, deployment guides, user guides and the license agreement are available in the technical resources section.
Most computers will open PDF documents automatically, but you may need todownload Adobe Acrobat Reader.
System requirements for the OnDemand Suite are:
The suite is also available as a desktop application.
Links in Flash movies should be duplicated as plain text links.
Add plain text links in the alternative HTML content for the Flash movie.
Note: Section 508 (2000) checkpoints (a) through (k) are equivalent to WCAG 1.0 level A checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccWcag1-1.1.12
Some table header cells have no corresponding data cells.
Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccHtmlTableMissingCells
Avoid using Flash movies that run for more than 5 seconds and don't allow users to pause or stop the animation.
If Flash plays an animation for more than 5 seconds, add a pause or stop button to the movie.
Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccWcag1-7.3.2
Element lang attribute contains an invalid language.
A BCP 47 lang attribute consists of hyphen-separated subtags. The first subtag identifies a natural language by its ISO 639 language code (e.g. en for English) and may be followed by additional subtags. The most common additional subtag is a two-letter ISO 3166 country code (e.g. GB for the United Kingdom to form en-GB). IANA maintains a registry of allowed subtags. A empty lang attribute is allowed (and means unknown language) but a lang containing only spaces is not allowed and causes a random language to be selected in a screen reader.
Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccHtmlElementLangInvalid
Control labels should be unique on a page, or be close to text providing context.
Controls with the same visible label need extra context (such as a heading) near the control to explain the differences between the fields. Note that aria-label does not set the visible label.
Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccHtmlFormControlDuplicateLabel
A style attribute with word-spacing: !important cannot be resized by assistive technology.
Ease-of-reading browser extensions inject CSS styles to increase line height and character spacing, but !important properties in style attributes cannot be overridden.
Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccCssWordSpacingImportant
A style attribute with line-height: !important cannot be resized by assistive technology.
Ease-of-reading browser extensions inject CSS styles to increase line height and character spacing, but !important properties in style attributes cannot be overridden.
Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccCssLineHeightImportant
A style attribute with letter-spacing: !important cannot be resized by assistive technology.
Ease-of-reading browser extensions inject CSS styles to increase line height and character spacing, but !important properties in style attributes cannot be overridden.
Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccCssLetterSpacingImportant
Content inserted with CSS is not read by some screen readers, and not available to people who turn off style sheets.
Move the content from CSS to the HTML page so that all users can see it.
Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccWcag2-F87-1
The headers attribute references a non-existent table header ID.
Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccWcag2-F90-1
role is ignored on this element.
The presentational roles role=presentation and role=none are ignored when applied to interactive elements like button and elements with global aria attributes like aria-label. This also happens when img alt='' is used with global aria attributes.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccAriaRoleConflict
ARIA role=menuitem element is empty and has no accessible name.
A name allows screen readers to voice what the control does. To add a name do one of the following:
aria-label attributearia-labelledby attributeimg alt attribute if the menuitem contains an img elementNote: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccAriaMenuitemBlank
This posting summarizes some detailed research into the state of government accessibility standards around the world, as of March 2016. Usually these evolve fairly slowly, although the Jodhan vs. Attorney General of Canada case may change that (governments don't like being successfully sued by their citizens).
In general, these standards apply to government agency websites (and not commercial web sites) with the exception of Australia and Norway where commercial sites are also required to comply. Other countries have disability discrimination laws which cover websites, but these don't specify the technical standards required to comply with the law.
This table shows government accessibility standards, and relevant legislation, in 18 territories:
| Country | Standard | Legislation | Applies to |
|---|---|---|---|
| Australia | WCAG 2.0 AA | Disability Discrimination Act 1992 | All government and non-government websites should comply with WCAG 2.0 AA by end of 2013 |
| Canada | WCAG 2.0 AA | Human Rights Act 1977 | Common Look and Feel 2.0 required WCAG 1.0 up till July 2011 for all government websites. The Jodhan vs. Attorney General of Canada ruling requires the Canadian government to update the guidelines to WCAG 2.0, and this was implemented as the Standard on Web Accessibility on Aug 1, 2011. |
| EU | WCAG 2.0 AA | European Parliament Resolution (2002) 0325 † | Required for all EU commission websites - see EUROPA - Web accessibility policy. |
| France | RGAA 4 (based on WCAG 2.1) | Law No 2005-102, Article 47 | Updated from RGAA 2.2 in April 2015, to take account of new technologies like HTML5 and ARIA. RGAA 2.2 was required for all French central government websites by May 2011. All other French public websites (public services, towns, public research, etc) are required to comply by May 2012. The RGAA 4.0 update aligned the standard with WCAG 2.1. |
| Germany | BITV 2 (based on WCAG 2.0) | Federal Disabled Equalization Law (BGG) | BITV 2 came into force on Sept 22, 2011, and is required for all government websites. It is based on WCAG 2.0, but not identical. |
| Hong Kong | WCAG 2.0 AA | WCAG 2.0 AA became the standard for GovHK websites in March 2012. | |
| India | Guidelines for Indian Government Websites (based on WCAG 2.0 Level A) | WCAG 2.0 Level A became the standard for Indian government websites in February 2009. | |
| Ireland | WCAG 2.0 AA | The Disability Act 2005 | All government websites - Universal Design Guidance for Online Public Services 2.10 |
| Israel | WCAG 2.0 AA | Equal Rights of Persons with Disabilities Law, 5758-1998 | All government websites, and websites of businesses with annual turnover of 500,000 ILS (approx USD $125,000) - Israeli Standard 5568 |
| Italy | Technical Rules of Law 4/2004 (updated to WCAG 2.0 in September 2013) | Law No. 4/2004 (Stanca Law) | Required for all government websites |
| Japan | X 8341-3:2016 (identical to WCAG 2). | Identical to ISO/IEC 40500:2012, which is itself identical to WCAG 2.0. Required for all local and central government websites. Commercial websites are also encouraged to use it. | |
| Netherlands | WCAG 2.0 AA | Government websites must comply with the government web guidelines, which include WCAG 2.0 AA. There are no requirements for non-government websites. | |
| New Zealand | WCAG 2.0 AA | Human Rights Amendment Act 2001 | Web Accessibility Standard 1.1 (WCAG 2.1 AA with some exceptions) required for all government web sites. |
| Norway | WCAG 2.0 AA (with exceptions) | LOV 2008-06-20 nr 42Lov om forbud mot diskriminering på grunn av nedsatt funksjonsevne | The law requires all websites to be be universally designed. From July 2013, new websites should follow WCAG 2.0 AA with some exceptions regarding time-based media and social media. |
| Ontario | AODA (WCAG 2.0 AA) | Required for all new Ontario government websites by January 2012, and existing government websites by January 2016. | |
| Quebec | SGQRI 008 (based on WCAG 2.0) | Standards sur l'accessibilité du Web | Custom made standard based on WCAG 2.0 with specifics covering websites, downloadable documents and multimedia. |
| Spain | UNE 139803:2012 (updated in 2012 to WCAG 2.0 AA) | Law 34/2002, Law 51/2003 | Required for all government websites. No mandatory requirements on non-government websites. |
| United Kingdom | WCAG 2.1 AA | Equality Act 2010 | The GDS Service Manual requires WCAG 2.1 AA as a starting point for UK government web sites. Other UK websites need to comply with the Equality Act and provide equal access, but this doesn't specify technical standards. |
| USA | Section 508 - 2017 Refresh (incorporates WCAG 2.0 AA) | Section 508 of Rehabilitation Act | US federal agencies' websites must comply with Section 508 guidelines. These were updated in January 2017 and agencies should comply with the revised guidelines by January 18, 2018. |
† Irony Alert: the European resolution insists web site documents should be clear and simple, but kicks off with 22 paragraphs of incomprehensible bureaucratic text. Here's an example:
whereas the internet as a part of society is an instrument for society as a whole, so it is fundamental that technologically neutral access to public information is offered for all groups in society...
The key takeaway from this research: adoption of WCAG 2 is progressing steadily and becoming increasingly important:
This post is a compilation of disability statistics from government agencies and researchers in the US, UK and Canada. The statistics shown have most impact on website use, and help assess the impact of accessibility problems, in terms of numbers of people affected, and likely commercial impact.
| Reading difficulties |  | Up to 10% of people in the US have reading difficulties, including dyslexia (source: dyslexiahelp.umich.edu). A study in 2009 by Cass Business School found that around 20% of UK entrepreneurs and 35% of US entrepreneurs are dyslexic (Bill Gates and Richard Branson are textbook examples). |
|---|---|---|
| Color blindness |  | 8% of caucasian males in the US suffer from some form of color blindness, compared to 0.5% of females. (source: nei.nih.gov). Incidence of color blindness differs between ethnic groups - from 1% in Inuit to 8% in Caucasian males. |
| Dexterity difficulties |  | 7% of working age adults have a severe dexterity difficulty (source: The Wide Range of Abilities and Its Impact on Computer Technology - Microsoft / Forrester). Severe dexterity difficulties mean users are unlikely to use a mouse, and rely on the keyboard instead. |
| Difficulty hearing |  | 4%-5% of people in the US, UK and Canada suffer from difficulty hearing (sources: census.gov, Statistics Canada, UK ONS) Incidence increases sharply in over-60s, with more than 20% of over-75s affected. |
| Difficulty seeing |  | 3%-4% of people in the US, UK and Canada can't see well enough to read (sources: census.gov, Statistics Canada, UK ONS) Incidence increases with age, with more than 10% of over-70s affected. |
Note: Government statistical agencies produce these numbers from questionnaires, but questions aren't standardized between countries, so figures are not directly comparable from country to country. For example, the questions"do you have difficulty seeing" and "do you have difficulty seeing newsprint" produce different response rates.
Hearing and sight becomes poorer as people get older, but these same people often have large amounts of disposable income
and leisure time. This presents particular challenges for web sites selling items which appeal to an older demographic,
such as travel and cruises (source: census.gov).