Beeper or Buzzer for the motherboard, used for diagnostic checks during the computer's POST. It connects to the 4-pin Speaker header, which is usually found at the bottom of a motherboard, also known as JFP1 (Jumper Front Panel), exactly next to the connections for the PC Case cables (Computer Case) Power SW, Reset SW, HDD LED, Power LED or PWR LED.

It is a way to check that our PC is functioning correctly. Usually, when we hear 1 beep, the computer's operation is smooth and the boot is successful. Each motherboard has different beeps depending on the manufacturer. Ideally, you should refer to the manual that came with your motherboard to identify any errors during POST.