It is used to move or rename files.
mv filename1 [filename2...] target_file
The command mv is used to move files around the system. A user can move a file to another filename by typing mv filename target_filename. If the target_file already exists, it is overwritten. A user can also move a file or files to another directory, by using the mv command. To move files to another directory type mv filename1 [filename2...] directory_path. For more information see the UNIX man page on mv.