Versioning is a system for software developers to support collaborative development in a team and track changes to source code over time from multiple developers. MPLAB® X IDE supports version control through a variety of third-party tools. Below are several links to help you get started with these tools. This list is by no means comprehensive but should provide a good starting point.
Git
Git Website
Wikipedia: Git
Git Tutorial
Using Git Support in NetBeans IDE
Subversion®
Apache™ Subversion® Website
Wikipedia: Apache™ Subversion®
Version Control with Subversion®
Using Subversion Support in NetBeans IDE
Mercurial
Mercurial Website
Wikipedia: Mercurial
Hginit: Mercurial tutorial
Using Mercurial Support in NetBeans IDE
CVS (supported through a plugin)
CVS - Concurrent Versions System
Wikipedia: Concurrent Versions System
Source Forge: What is CVS?
Using CVS Support in NetBeans IDE
MPLAB X IDE is based on the NetBeans platform.