By definition, semantics refers to the correct interpretation of the meaning of a word or sentence. To use a word semantically is to use it in a way that properly lines up with the meaning of the word. alot of HTML tags have semantic meaning. the element itself conveys some information about the type of content contained between the tags. thus semantic markup is about using HTML elements according to their intented purpose. it also requires the seperation of content and presentation.
Section 508 is an amendment to the United States Workforce Rehabilitation Act of 1973. It is a federal law mandating that all electionic and information technology developed, procured, maintained,or used by the federal government to be accessible to people with disabilities.
Search Engine Optimization is the process of getting traffic from the "free", "organic", "editorial", or "natural" search results on search engines. this makes it possible to make website search engines more accurate and precise, allowing users ease of access in a streamlined fashion.
Semantic markup, section 508, and Search Engine Optimization all come together to make websites better for everyone. it allows information to be accesed by the general public and even allow people with certain disabilities to navigate and use search engines as well as anyone else.