One of the entitlements most new military personnel want to learn about is LEAVE. Leave is paid vacation from duty for recreation and relief from the pressures of job-related duties. You may also take leave for personal reasons and emergency situations. A "pass" (called "liberty" in the Navy, Coast Guard, and Marine Corps) is time-off, not chargeable as leave.
Leave is a RIGHT (not a privilege) that is granted by Congress under Federal Law.

While leave is a RIGHT, that doesn't necessarily mean you can take it whenever you wish. As with all things, "military necessity" determines when you can take your leave.