Monitor may have one of the following meanings:

• A computer display
• A concurrent programming language construct which encapsulates variables, access procedures and initialisation code within an abstract data type. The monitor's variable may only be accessed via its access procedures and only one process may be actively accessing the monitor at any one time. The access procedures are critical sections. A monitor may have a queue of processes which are waiting to access it. Monitors in this sense were invented by C. A. R. Hoare.
• A hardware device that measures electrical events such as pulses or voltage levels in a digital computer.
• To oversee a program during execution. For example, the monitor function in the Unix C library enables profiling of a certain range of code addresses. A histogram is produced showing how often the program counter was found to be at each position and how often each profiled function was called.
• A control program within the operating system that manages the allocation of system resources to active programs.
• A machine code monitor used by programmers to modify computer memory contents and enter and modify assembly language programs.
• A program that measures software performance.
• USS Monitor, the ironclad warship of the American civil war.
• A monitor warship type of ship based on the USS Monitor and built by several navies for coastal defence in the 1860s and 1870s.
  It reappeared in a different form during the First World War.
• A large tropical lizard (family Varanidae); see monitor lizard

This is a disambiguation page