In SEO, structured data is a method of tagging the content on your page to present it in an easier-to-digest manner. The way this is done is through, essentially an online dictionary for those tags sometimes referred to as schema or markup.

Using schema can help improve your search appearance because search engines better understand what directly corresponds to what. For example, if you are using product schema, the search engine will be able to more easily understand the price, availability, item condition, review ratings and so on, and can show all of this information in search.