CCD stands for charge-coupled device, and refers to a type of image sensor in a digital camera. CCD sensors capture light on individual pixel sensors, which convert them into electrical signals. CCD sensors capture this light at one time, which eliminates the risk of rolling shutter effects, but may also overexpose the cells and cause blooming. Once the light information is captured, each row is processed by a read out register, while each remaining row moves down to fill the empty spaces. This results in a slower readout than the CMOS sensor. CCD sensors are much more mature and generally produce higher quality images, though CMOS sensors are quickly closing the gap.