Mitochondria are double-membraned organelles found in the cells of most eukaryotic organisms, often referred to as the "powerhouses of the cell." They generate adenosine triphosphate (ATP), the primary energy currency of the cell, through a process called cellular respiration. Besides energy production, mitochondria play roles in regulating metabolic processes, apoptosis (programmed cell death), and maintaining cellular health. Their unique DNA and ability to replicate independently suggest an evolutionary origin linked to ancient symbiotic bacteria.