A power conditioner is a device that improves the quality of power delivered to electrical loads. It regulates voltage levels and filters out problems like noise, transients, and power factor issues to provide clean AC power. Power conditioners vary in size and functionality depending on their intended use, from small units that mount on circuit boards to large industrial models. They help ensure equipment receives stable power that meets specifications, as real-world power supplies can deviate from ideals with fluctuations, harmonics, impedance variations, and other quality issues.