A thermal cycler, also known as a thermocycler, PCR machine, or DNA amplifier, is a laboratory device used primarily to amplify DNA segments through the polymerase chain reaction (PCR). The machine features a thermal block with slots for tubes containing reaction mixtures. It precisely raises and lowers the block’s temperature in pre-programmed steps to facilitate the PCR process. Besides DNA amplification, thermal cyclers are also used for other temperature-sensitive reactions, such as restriction enzyme digestion and rapid diagnostics, making them indispensable in molecular biology labs.