Originally released in 2002 for the Mac Operating System, the hardware monitor was designed to keep track of various functionalities and states of all the hardware sensors available in the computer. It was later made available to other operating systems. The hardware monitor is responsible for reading and visually displaying or exporting data values that it receives from sensors.

This includes the following sensor types:

• Battery data of portable computers
• Voltage sensors
• Current (amperage) sensors
• Fan speed sensors
• Sensors for pulse-width controlled fans
• Power and load sensors
• Ambient light sensors
• User-defined artificial sensors to monitor the operating system