Revision control, version control or source control is way of tracking of changes to documents, computer programs, large web sites,Source Code and other collections of information.Version control systems (VCS) most commonly run as stand-alone applications, but revision control is also embedded in various types of software such as word processors and spreadsheets.Different versions of a document is referred as revision each revision has a revision number.
A version control system is a repository of files.Every change made to the file is tracked, with who made the change, why they made it, and references to problems fixed, or enhancements introduced, by the change.
Revision control manages changes to a set of data over time. These changes can be structured in various ways.There are many version controlling systems are available in market.
Company XYZ is developing a project ABC in Java.There a many files to store and preserve and Many developers are working on same java files.This project is using SVN to store and track changes in Java files.A developer make changes in file helloworld.java and store it in SVN.Another developer go to SVN and checkout helloworld.java,make changes and again store it in SVN.Every time any one want to make changes he/she can go to SVN check out file make changes and save it back to SVN.SVN create a revision every time any one save same file.So data can be preserved.