What is chmod?

chmod (stands for "change mode") is a command that defines access permissions in UNIX-based operating systems (UNIX, Linux, FreeBSD, Mac OS). chmod command is usually used with a 3-digit value (each digit corresponds to an octal number ranging from 0 to 7) to set/modify access permissions for files and directories. You can obtain more information on the chmod command and its usage at http://en.wikipedia.org/wiki/Chmod.