Web accessibility encompasses all barriers that may hinder users from accessing the site. This includes things such as navigating, perceiving and interacting with the web.
Besides general users, web accessibility is particularly focused on helping those with disabilities that are at more disadvantage when using a website. Therefore, content design strategy revolves around promoting overall usability for all. For example, including assistive technologies such as an HTML alternative text that could be viewed by those who may have a visual impairment.
A single International web content standard has been created to tackle that very issue. The Web Content Accessibility Guideline, simply known as the WCAG, has been developed by the W3C(World Wide Web Consortium), the international governing body of the web, to help developers create web content that is friendly to all users.