What is a color filter? What is its function when taking pictures?

Color filters are also called "filters". An optical device that selectively absorbs (or passes through) light according to different wave bands. It consists of a mirror ring and a filter, and is usually installed in front of a camera or camera lens. The color filter for black-and-white photography is mainly used to correct the color sensitivity of black-and-white film, adjust the contrast and eliminate the interference light. Color filters for color photography are mainly used to correct the color temperature of light sources and make color compensation.