[h=2]About Data Highlighter[/h] Data Highlighter is a webmaster tool for teaching Google about the pattern of event-related data on your website. You simply use Data Highlighter to tag the data fields on your site with a mouse. Then Google can present your data more attractively -- and in new ways -- in search results and in other products such as the Google Knowledge Graph. For example, if you use Data Highlighter to tag data (name, location, date, and so on) for the events on your site, the next time Google crawls your site the event data will be available for rich snippets on search results pages:
Tried it, it is something similar with Google Rich Snippets or also called the "Microformats" a very useful tool for making your search results more obvious.