Web Accessibility: It is basically define in ternary ways which: Web page semiotics, application of browser, and assistive technology. Accessibility of web pages is depends on two important factors: WCAG and UAAG. WCAG is related to web page semiotics and their practices, whereas UAAG describe about implementation of web browsers in order to assistive technology.
WCAG: It show best practices on semiotics and best practices should be applied some checklist for evaluation. And evaluation is done in three ways:
Both usability test and analysis are mainly focus on final state of the web pages within browser. And automated evaluation is focused on implementation and content of web page which sent by first HTTP request.
Communication is depends on three main areas: Web pages, resources, and AJAX.
It comes after all the above processes, which is done in four steps execution before interaction with users. First is requests, which concerns with all resources which getting compose with web page. And all these resources parses which means it build the HTML DOM tree, the CSS objects model, and making execution plan which is based on existed script. After this browser forces two events in sequences DOM-ready and DOM-Load. DOM-ready for trigger after HTML tree and DOM-load is for CSS and images etc.
Basically accessibility of web is done by two process, one is Automated Accessibility and another is accessibility evaluation in browser. Automated accessibility is basically depends on software means here no need of human interventions. Here we explained it within two main different domain: First one is command line and second one is Browser. Command line domain shows evaluation is processed on HTML documents which is transferred for HTTP response at initial stage. But in browser domain evaluation is done with transformed version of HTML doc. This differences is better understand by architecture.
Architecture: For evaluation architecture is build with five component: Evaluator, Environments or domains, techniques, Formatters, and Web server.