The schema.org project is the result of cooperation between three giants from the IT industry:
Its goal is to create a structured data markup scheme that is supported by the most important search engines. Schema.org is a documentation of markup schemes that are supported by interoperating search engines. Such tags placed on a website help search engines interpret the information contained therein in order to provide even better (more relevant) search results.
Why use schema.org?
Using the schema.org format on websites allows you to add additional information to the website's HTML code. Search engines do not think, so they have a very limited ability to analyze the content of a website. It usually comes down to the so-called "Exact Match" of the website content and the links leading to it. By supplementing the website with additional tags, we can inform the search engine about the type of the described element:
This allows the search engine to display the content of the website in a content-appropriate, useful way. Search engines use structured data markup contained in a website in many ways. E.g.: Google uses them to generate rich snippets in search results.