It is every site owner’s responsibility to make your individual site’s content accessible to individuals with sensory or physical impairments, thus all sites must follow Marshall IT and Office of Communications [insert UCOMM accessibility standard]. WordPress offers some additional information about accessibility, which you can find here.
It is recommended to use some sort of Accessibility checker to test each aspect of what goes into making a web page accessible, some very informative and useful ones are:
WAVE: Web Accessibility Evaluation Tool
A more comprehensive list of Web Accessibility Evaluation Tools