criticism of the W3C process, claiming that it does not sufficiently put the user at the 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 WAI has been criticised for allowing WCAG 1.0 to get increasingly out of step with today's technologies and techniques for creating and consuming web content, for the slow pace of development of WCAG 2.0, for making the new guidelines difficult to navigate and understand, and other argued failings. Essential components of web accessibility The accessibility of websites relies on the cooperation of several components: content – the information in a web page or web application, including natural information (such as text, images, and sounds) and code or markup that defines structure, presentation, etc. web browsers, media players, and other "user agents" assistive technology, in some cases – screen readers, alternative keyboards, switches, scanning software, etc. users' knowledge, experiences, and in some cases, adaptive strategies using the web developers – designers, coders, authors, etc., including developers with disabilities and users who contribute content authoring tools – software that creates websites evaluation tools – web accessibility evaluation tools, HTML validators, CSS validators, etc. Guidelines for different components Authoring Tool Accessibility Guidelines (ATAG) ATAG contains 28 checkpoints that provide guidance on: producing accessible output that meets standards and guidelines promoting the content 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 aim; 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 updated whereas the principles, guidelines and success criteria 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 content