rsync is a widely-used utility to keep copies of a file on two computer systems the same. It is commonly found on Unix-like systems and functions as both a file synchronization and file transfer program. The rsync algorithm, a type of delta encoding, is used to minimize network usage. Zlib may be used for additional compression, and SSH or stunnel can be used for data security.rsync is typically used to synchronize files and directories between two different systems.