Schema are html tags that are recognized by all three major search engines Google, Yahoo and Bing. These tags are in reality guide to content pages for search engine and help improve search quality. On Page markup help the search engines to better understand the contents or topics especially in case of large data base driven sites or sites using CMS.
Almost all web masters understand the importance of H1 tag that specify the importance of a particular topic related to the page. But deeper meaning is not delivered by the H1 tag alone.
Hence people may understand the meaning of the word or semantics. But the search engine may not understand the exact meaning often. Hence specifying you web page content using microdata and vocabulary will help in getting better indexing on SERPs.
The HTML tags here simply provide greater and exact meaning of the keyword or web page contents to the search engine. For better understand please click on the link below:
The Schema website offers good information as to the importance of microdata and how to include tags using the vocabulary. .