3.1.1 Language of Page: The default human language of each Web page can be programmatically determined. (Level A)
This success criterion requires that each web page of a site has its default human language programmatically defined. This, according to the Internationalization best practices plays a critical role in determining the default text-processing language. Apart from this, this is a key factor for screen readers to switch to the correct reading language, load correct pronunciation rules of language variations. Traditional browsers can render the text correctly and visual browsers can load characters and scripts appropriately. Thus language of page helps people with disabilities understand content in a better way.