Schema markup is code (semantic vocabulary) that you put on your website to help the search engines return more informative results for users. If you've ever used rich snippets, you'll understand exactly what schema markup is all about. Extra information found on search result page, like star rating, address, events, call to action button etc are formed from schema markups. Even schema have influence on Google knowledge graph. By using this tool, you can simply generate schema markup of a article based webpage.