cwRsync is a packaging of Rsync for Windows with a client GUI. You can use cwRsync for fast remote file backup and synchronization.
Rsync uses the Rsync algorithm which provides a very fast method for bringing remote files into sync. It does this by sending just the differences in the files across the link, without requiring that both sets of files are present at one of the ends of the link beforehand. At first glance this may seem impossible because the calculation of diffs between two files normally requires local access to both files.
Rsync normally uses ssh for communication. It requires no special privileges for installation. You must, however, have a working ssh system. Alternatively, rsync can run in `daemon' mode, listening on a socket. This is generally used for public file distribution, although authentication and access control are available.
Cygwin is a Linux-like environment for Windows. It consists of a DLL (cygwin1.dll), which emulates substantial Linux API functionality, and a collection of tools.