Power On Self-Test. Checks the basic system functions (RAM, processor, drives, system interface, etc.) before attempting to load an operating system. If POST fails, the system will normally halt and may produce a series of beeps from the computer speaker which can help indicate the cause of the problem. An add-in diagnostic card can also be installed in one of the PCI (or ISA on older systems) slots which can display the POST error code on an LED or LCD display.
