Unison is a file-synchronization tool for Unix and Windows. It allows two replicas of a collection of files and directories to be stored on different hosts (or different disks on the same host), modified separately, and then brought up to date by propagating the changes in each replica to the other.
Unison that is available for Linux, Unix and Windows, shares a number of features with tools such as CVS, PRCS, Subversion, BitKeeper, distributed filesystems (e.g. Coda), uni-directional mirroring utilities (such as rsync), and other synchronizers (Intellisync, Reconcile, etc).
This article tells how to sync data between Desktop PC and laptop with Unison.