Open Graph meta tags allow a web page to be interpreted/rendered nicely by social media platform, such as Twitter, Facebook (who originally created it), etc.
It's as simple as putting some
<meta property="og:xxx" content="..."/> in the
<head> of an HTML page, where
xxx can be
Another proposal to add information to web pages is JSON for Linking Data (JSON-LD). Here the focus is on machine-readable meta data for a person, place, event, product, recipe, etc. Yet another is Twitter Cards.