CCD (charge-coupled device) is a type of image sensor. In effect, it is the "eye" of a camera phone, digital camera, or video camera. It is a device similar to a computer chip, which senses light focused on its surface, like electronic film.
CCD is one of two main types of image sensor. The other type is CMOS.
CCD sensors have historically provided better image quality, although the newest and best CMOS sensors match CCD quality.
CCD sensors require some additional circuitry compared to CMOS sensors, which can have a minor negative impact on size, cost, and battery life in small devices such as camera phones.