Three levels of accessibility for the Web.Nowadays with the growing level of technology, all groups of people should have equal access to information. To make this possible World Wide Web and Web Browsers should be adapted to needs of people with disabilities. These group of people may require special mobile devices, applications and tools as well as accessible websites and web content. In 1997 The World Web Consortium (W3C) launched the Web Accessibility Initiative (WAI) which consisted of different working groups trying to improve web accessibility such as “web content, web browsers, media players, authoring tools and evaluation tools” ( ).Two years later with the efforts of Working groups and Special Interest Groups of WAI, a Web Content Accessibility Guidelines 1.0 was issued. Then in 2008 the Web Content Accessibility Guidelines 2.0 was published. So far it is used as a set of standards for web accessibility all over the world. WCAG 2.0 consists of 12 guidelines organized under four principles: perceivable, operable, understandable and robust. By perceivable WCAG 2.0 understands that all the information and user interface components must be presented to users in ways they can perceive, that is:text alternatives for any non-text content, alternatives for time-based media,content should be presented in different ways without losing information or structure,distinguish content to make it easier for users to sea and hear it.By operable principle WCAG 2.0 means that users interface components and navigation must be operable which can be reachable through:keyboard access,providing enough time for users to read and use content,content should not cause seizures,helping users to navigate easily.By understandable principle the standard sees that information and the operation of user interface should be understandable, which means:context to be readable and understandable,web pages to operate in predictable ways,possibility to avoid and correct mistakes.Content must be also robust enough that it can be interpreted reliably by a wide variety of user agents, such as assistive technologies, that is – maximizing compatibility. ( 2.0. also outlines three basic levels of accessibility:Level A (lowest) – the most basic level of web accessibility (this level is required for all the users to access the Web Content);Level AA (mid range)- deals with the biggest and most common barriers for disabled users (this level is required so all groups of users find it easy to access Web content);Level AAA (highest)- the highest and most complex level of web accessibility (The WCAG document does not recommend that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA success criteria for some content ) .The techniques for WCAG 2.0 are periodically updated whereas the principles, guidelines and success criteria are stable and do not change. (’s Web Accessibility Initiative works with organizations around the world to make the Web more accessible for people with disabilities and older users, they are also constantly looking for volunteers to implement, promote and review guidelines. WAI also welcomes comments and ideas for new or updated techniques on the documents at any time. ( )


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