Web accessibility refers to the inclusive practice of removing barriers that prevent interaction with, or access to websites , by people with disabilities . When sites are correctly designed, developed and edited, all users have equal access to information and functionality.
For example, when a site is coded with semantically meaningful HTML , with textual equivalents provided for images and with terms that are meaningfully named, this helps users using text-to-speech software and / or text-to-Braille hardware. When text and images are large and / or enlargeable, it is easier for users to understand the content. When links are underlined (or otherwise differentiated), this ensures that color blind users will be able to notice them. When clickable links and areas are wide, this helps users Who can not control a mouse with precision. When pages are coded so that users can navigate by means of the keyboard alone, or a singleswitch access device alone, this helps users who can not use a mouse or even a standard keyboard. When videos are closed captioned or a language version is available, deaf and hard-of-hearing users can understand the video. When flashing effects are avoided or made optional, users prone to seizures caused by these effects are not put at risk. And when content is written in the same language and illustrated with diagrams and animations, users with dyslexia and learning difficulties are better able to understand the content. When sites are correctly built and maintained, all of these users can be accommodated without decreasing the usability of the site for non-disabled users.
The needs that Web accessibility aims to address include:
- Visual: Visual impairments including blindness , various common types of low vision and poor eyesight, various types of color blindness ;
- Motor / mobility: eg tremor, slowness muscle, loss of fine muscle control, etc., Parkinson’s Disease , muscular dystrophy , cerebral palsy , stroke ;
- Auditory: Deafness or hearing impairments , including individuals who are hard of hearing ;
- Seizures: Stock Photo epileptic seizures caused by visual strobe gold flashing effects.
- Cognitive / Intellectual: Developmental disabilities , learning disabilities ( dyslexia , dyscalculia , etc.), cognitive disabilities of various origins, affecting memory, attention, developmental “maturity,” problem-solving and logic skills, etc.
Assistive technologies used for web browsing
Individuals living with a disability using assistive technologies and following web browsing:
- Screen reader software, which can be read out, using a synthesized speech, or being able to read what is happening on the computer (used by blind and vision impaired users).
- Braille terminals, consisting of a refreshable braille display which renders text as braille characters (usually by means of raising pegs through holes in a flat surface) and a keyboard.
- Screen magnification software, which enlarges what is displayed on the computer monitor, making it easier to read for vision.
- Speech recognition software that can be used in the context of computer programming
- Keyboard overlays, which can make typing easier or more accurate for those who have motor control difficulties.
- Access to subtitled or sign language videos for deaf people.
Guidelines on accessible web design
Web Content Accessibility Guidelines
In 1999 the Web Accessibility Initiative , a project by the World Wide Web Consortium (W3C) published the Web Content Accessibility Guidelines WCAG 1.0 .
On 11 December 2008, the WAI released the WCAG 2.0 as a Recommendation. WCAG 2.0 aims to be up to date and more technology neutral. Though web designers can choose from standard, the WCAG 2.0 has been widely accepted as the definitive guidelines on how to create accessible websites. Governments are steadily adopting the WCAG 2.0 as the standard accessibility for their own websites.  In 2012, the Web Content Accessibility Guidelines were also published as an ISO / IEC standard: “ISO / IEC 40500: 2012: Information technology – W3C Web Content Accessibility Guidelines (WCAG) 2.0”. 
Criticism of WAI guidelines
It has been criticized by the W3C process, claiming that it does not enter the user’s heart of the process.  There Was a formal objection to WCAG’s original claim That WCAG 2.0 will address requirements for people with learning disabilities and cognitive limitations headed by Lisa Seeman and signed by 40 organizations and people.  In articles such as “WCAG 2.0: The new W3C guidelines evaluated”,  “To Hell with WCAG 2.0”  and “Testability Costs Too Much”,  the WCAG has been criticized for allowing WCAG 1.0 for the development of WCAG 2.0, for making the new guidelines difficult to navigate and understand argued failings.
In 2011, the Government of Canada has begun to provide accessible, usable, interoperable and optimized mobile devices. These standards replace Common Look and Feel 2.0 (CLF 2.0) Standards for the Internet.
The first of these four standards, Standard on Web Accessibility  . The Standard on Web Accessibility follows the Web Content Accessibility Guidelines (WCAG) 2.0 AA, and contains a list of exclusions that is updated Annually. It is accompanied by an explicit Assessment Methodology  that helps government departments comply. The government also developed the Web Experience Toolkit (WET),  a set of reusable web components for building innovative websites. The WET helps government departments build innovative websites that are accessible, usable and interoperable and therefore comply with the government’s standards. The WET is open source and available for anyone to use.
The three related web standards are: the Standard on Optimizing Websites and Applications for Mobile Devices,  the Standard on Web Usability  and the Standard on Web Interoperability. 
As part of the Web Accessibility Initiatives in the Philippines , the government through the National Council for the Welfare of Disabled Persons (NCWDP) board approved the recommendation of forming an ad hoc group of webmasters that will help in the implementation of the Biwako Millennium Framework set by the UNESCAP .
The Philippines was also the place where the Interregional Seminar and Regional Demonstration Workshop on Accessible Information and Communications Technologies (ICT) to Persons with Disabilities was held where eleven countries from Asia – Pacific were represented. The Manila Accessible Information and Communications Technologies Design Recommendations was drafted and adopted in 2003.
In Spain, UNE 139803 is the norm entrusted to regulate web accessibility. This standard is based on the Web Content Accessibility Guidelines 1.0. 
In Sweden, Verva, the Swedish Administrative Development Agency is responsible for a set of guidelines for public sector websites. Through the guidelines, web accessibility is presented as an integral part of the overall development process and not as a separate issue. The Swedish guidelines contain criteria which cover the entire lifecycle of a website; from its conception to the publication of live web content. These criteria address several areas which should be considered, including:
- web standards
- privacy issues
- architecture information
- developing content for the web
- Content Management Systems (CMS) / authoring tools selection.
- development of web content for mobile devices.
An English translation was released in April 2008: Swedish National Guidelines for Public Sector Websites.  The translation is based on the latest version of the Guidelines which was released in 2006. 
In December the UK released the standard BS 8878: 2010 Web accessibility. Code of practice . This standard effectively supersedes PAS 78 (2006). PAS 78, produced by the Disability Rights Commission and sand by disabled people. The standard has been designed to provide non-technical professionals with improved accessibility, usability and experience for disabled and older people.  It will be particularly beneficial to anyone who gives guidance on process, rather than on technical and design issues. BS 8878 is consistent with the Equality Act 2010 and is referenced in the UK government’s e-Accessibility Action Plan. It includes recommendations for:
- Involving disabled people in the development process and using automated tools to assist with accessibility testing
- The management of the guidance and process for upholding existing accessibility guidelines and specifications.
BS 8878 is intended for anybody responsible for the policies of their organization, and governance over those policies. It is more or less responsible for promoting and supporting equality and inclusion initiatives within organizations and people involved in the procurement, creation or training of web products and content. A summary of BS 8878  is available to help organizations better understand how to use the standard in their business-as-usual processes.
Web Content Accessibility Guidelines in Japan were established in 2004 as JIS ( Japanese Industrial Standards ) X 8341-3. JIS X 8341-3 was revised in 2010 to adopt WCAG 2.0. The new version, published by the Web Accessibility Infrastructure Commission (WAIC), has the same four principles, 12 guidelines, and 61 success criteria as WCAG 2.0 has. 
Essential components of web accessibility
The accessibility of websites connected to the cooperation of eight components: 
- the website itself – natural information (text, images and sound)
- user agents, such as web browsers and media players
- assistive technologies, such as screen readers and input devices
- users’ knowledge and experience using the web
- authoring tools
- evaluation tools
- a defined web accessibility standard, or a policy for your organization (against which to evaluate accessibility)
These components interact with each other to create an environment that is accessible to people with disabilities.
Web developers usually use authoring tools and evaluation tools to create Web content .
People (” users “) use Web browsers , media players , assistive technologies or other ” user agents ” to get and interact with the content . ” 
Guidelines for different components
Authoring Tool Accessibility Guidelines (ATAG)
- ATAG  contains 28 checkpoints that provide guidance on:
- providing accessible output that meets standards and guidelines
- promoting the author author for accessibility-related information
- providing ways of checking and correcting inaccessible content
- integrating accessibility in the overall look and feel
- making the authoring tool itself accessible to people with disabilities
Web Content Accessibility Guidelines (WCAG)
- WCAG 1.0: 14 guidelines that are general principles of accessible design
- WCAG 2.0: 4 principles that form the foundation for web accessibility; 12 guidelines (untestable) that are goals for which authors should and 65 testable success criteria.  The W3C’s Techniques for WCAG 2.0  is a list of techniques that support authors to meet the guidelines and success criteria. The techniques are periodically stable and the principles are stable and do not change. 
User Agent Accessibility Guidelines (UAAG)
- UAAG  contains a comprehensive set of checkpoints that cover:
- access to all content
- user control over how is rendered
- user control over the user interface
- standard programming interfaces
Web accessibility legislation
Because of the growth in internet use  and its growing importance in everyday life. One approach is to protect access to websites for people with disabilities. Some countries, like the US, protect access for people with disabilities through the technology procurement process.  It is common for nations to support and adopt the Web Content Accessibility Guidelines (WCAG) 2.0 by referring to the guidelines in their legislation.   
In 2000, an Australian blind man won a $ 20,000 short box against the Sydney Organizing Committee of the Olympic Games (SOCOG) . This was the first successful box under the Disability Discrimination Act 1992 because of the Olympic Games , which is accessible to the blind users. The Human Rights and Equal Opportunity Commission (HREOC) also published World Wide Web Access: Disability Discrimination Act Advisory Notes.  All Governments in Australia also have policies and guidelines that require accessible public websites; Vision Australia maintain a complete list of Australian web accessibility policies.
In Brazil , the federal government published on January 18, 2005, for public reviewing. On 14 December of the same year, the second version was published, including suggestions made to the first version of the paper. On May 7, 2007, the accessibility guidelines of the paper become compulsory to all federal websites. The current version of the paper, which follows the WCAG 2.0 guidelines, is named e-MAG, Model of Acessibilidade of Governo Eletrônico (Electronic Government Accessibility Model), and is maintained by Brazilian Ministry of Planning, Budget, and Management .
The paper can be viewed and downloaded at its official website. 
In February 2014, the European Parliament has been established by the European Parliament, which is accessible to everyone. 
On 26 October 2016, the European Parliament accepted the directive that it should be accessible. They are described in the European standard EN 301 549 V1.1.2 (published by ETSI ). EU member states are expected to bring into force by 23 September 2018 laws and regulations that enforce the relevant accessibility requirements. September 2018; mobile apps by 23 June 2012. Some categories of websites and apps are excepted from the directive, for example “websites and mobile applications of public service broadcasters and their subsidiaries”. 
The European Commission’s “Rolling Plan for ICT Standardization 2017” notes that ETSI standard EN 301 549 V1.1.2 will need to be updated to include accessibility requirements for mobile applications and evaluation methodologies to test compliance with the standard. 
In Ireland , the Disability Act 2005  requires that the public communicates in a communicable manner. technology is available “(Section 28 (2)). The National Disability Authority has produced a Code of Practice giving guidance to public bodies on how to meet the obligations of the Act. This is an approved code of practice and its provisions. It states that a public body can achieve compliance with Section 28 (2) by “reviewing existing practices for electronic communications in terms of accessibility against relevant guidelines and standards”, giving the example of “Double A conformance with the Web Accessibility Initiative” (WAI) Web Content Accessibility Guidelines (WCAG) “.
The Israeli Ministry of Justice, which is based on the Israeli Standard 5568, which is based on the W3C Web Content Accessibility Guidelines 2.0. The main differences between the standard Israeli and the W3C standard relate to the requirements to provide captions and texts for audio and video media. The Israeli standards are somewhat more relevant, reflecting the current technical difficulties in providing such captions and texts in Hebrew. 
In Italy, web accessibility is ruled by the so-called ” Legge Stanca ” (Stanca Act), formally Act n.4 of 9 January 2004, officially published on the Gazzetta Ufficiale on 17 January 2004. The original Stanca Act was based on the WCAG 1.0. The standards have been updated to the WCAG 2.0.
In Norway, web accessibility is a legal obligation under the Act June 20, 2008 No 42 relating to a prohibition against discrimination on the basis of disability, also known as the Anti-discrimination Accessibility Act. The Act went into force in 2009, and the Ministry of Government Administration, Reform and Church Affairs [Fornyings-, administrasjons- og kirkedepartementet] published the Regulations for Universal Design of Information and Communication Technology (ICT) solutions [Forskrift om universell utforming av informasjons – og kommunikasjonsteknologiske (IKT) -løsninger] in 2013.  The regulations require compliance with Web Content Accessibility Guidelines 2.0 (WCAG 2.0) / NS / ISO / IEC 40500: 2012, level A and AA with some exceptions.  The Norwegian Agency for Public Management and eGovernment (Difi) is responsible for overseeing that ICT solutions are aimed at the general public in compliance with the legislative and regulatory requirements. 
In the UK , the Equality Act 2010 makes it illegal to discriminate against people with disabilities. The Act applies to the business of providing a service; public, private and voluntary sectors. The Code of Practice: Rights of Access – Goods, Facilities, Services and Premises paper  published by the government’s Equality and Human Rights Commission to Accompany the Act does Refer Explicitly to websites as one of the “services to the public the” which shoulds be considered covered by the Act.
United States of America
In the United States , Section 508, Rehabilitation Act of 1973 requires all federal agencies to provide access to those with disabilities. Both members of the public and federal employees have the right to access this technology, such as computer hardware and software, websites, phone systems, and copiers.  Also, Section 504 of the Rehabilitation Act prohibits discrimination against the funding of federal funds by the federal government and the federal government.
In addition, Title III of the Americans with Disabilities Act (ADA) prohibits discrimination on the basis of disability. There are some courts on the subject, multiple courts and the US Department of Justice have taken the position that the ADA requires a website and operators and owners to take affirmative steps to make their websites and apps accessible to disabled persons and compatible with common assistive technologies such as the JAWS screen reader, while others have taken the position that the ADA does not apply online. The US Department of Justice has endorsed the standard WCAG2.0AA as an appropriate standard for accessibility in multiple settlement agreements.  
Website accessibility audits
A growing number of organizations, companies and consultants offer website accessibility audits . These audits, a type of system testing , identify accessibility problems that exist within a website, and provide advice and guidance on the steps that need to be taken to correct these problems.
A range of methods are used for websites for accessibility :
- Automated tools are available which can identify some of the problems that are present. Depending on the tool the result is difficult to compare test results. 
- Expert technical reviewers, knowledgeable in web design technologies and accessibility.
- User testing, usually overseen by technical experts, deals with the role of the user.
Each of these methods has its strengths and weaknesses:
- Automated tools can process many pages in a relatively short length of time, but can only identify some of the accessibility problems that might be present in the website.
- Technical expert review will identify many of the problems that exist, but the process is time consuming, and many websites are too large to make it possible.
- The purpose of the test is to provide guidance to the user and to the extent that the user is aware of the situation.
Ideally, a combination of methods should be used to assess the accessibility of a website.
Remediating inaccessible websites
Once an accessibility audit has been conducted, and accessibility errors have been identified, the errors will need to be remediated in order to ensure the site is compliant with accessibility errors. The traditional way of correcting an inaccessible site is to go back to the source code, reprogram the error, and then test to make sure the bug was fixed. If the website is not scheduled to be revised in the near future, that error (and others) would probably remain on the site for a possible period of time, possibly violating accessibility guidelines. Because this is a complicated process, many website owners choose to go to a new site design or re-launch, as it can be more efficient to develop the site to comply with accessibility guidelines, rather than to remediate errors later.
Accessible Web applications and WAI-ARIA