Schema markup is a piece of code you can add to a page’s HTML to help search engines understand what is your website about and what type of information it contains. It pairs up words with specific values that help the search engines to categorize and index your content. Basically, instead of hoping Google understands what you are, you tell it directly through pieces of code that the search engine robots are able to read, process and use to return more informative results to users. For example, if you’re a dentist or brick and mortar store you might want to point that out using the proper tags so you won’t have to rely solely on keywords. If you want to check which are Schema markups available and how to add the relevant ones to your website, check out their official website.
(this definition was submitted by Jessica from Guarana Technologies, a mobile app development agency based in Canada)