Emmet(formerly Zen coding) is a set of plug-ins for text editors that allow for high-speed coding and editing in HTML, XML, XSLT and other structured code formats via content assist.
It uses a specific syntax in order to expand small snippets of code, similar to CSS selectors, into full-fledged HTML code and it also includes wrapping a section of code with expanded code.
The HTML pair matcher allows the user to locate the matching open/close tag for the tag at the current cursor position.
Unlike other HTML pair matchers, Emmet searches from the cursor's current position rather than scanning the document from the begining.

What is Emmet?