Semantic SEO is the practice of optimizing a website so that its content is more easily understood by search engines. This can be done by adding specific keywords and phrases to titles, headings, and other sections of the website, as well as by using semantic markup language like HTML5. Semantic SEO can also be used to improve the readability of websites by human beings.
Semantic search queries ask the question to get better results. For example, instead of asking "How tall is LeBron James?", you would ask "How tall is he?". The answer should be much more relevant to what people are actually looking for (he's 6'8").
Adding markup to your content can help search engines better understand the topic and intent of your page. This, in turn, can result in more relevant search engine results for your visitors.