chown command

How do I use chmod and chown command under Linux?

A. Use chown command to change file owner and group information. Use chmod command to change file access permissions such as read, write etc.
chown command

chown command changes the user and/or group ownership of each given file.

For example following command will setup user and group ownership to root user only for /backup directory:
# chown root:root /backup
Set user user ownership to root user and allow any member of ftp group to access file.txt (provided that they have sufficient read/write rights).
# chown root:ftp /home/data/file.txt