Lawrence Berkeley National Laboratory

We review recent progress in the field, using as a framework a partial list of present limitations and problems: CCD and mosaic size, packing fraction in mosaics, red response and fringing, and intrinsic point-spread function due to lateral charge diffusion. Related topics such as orthogonal-transfer CCDs and the special requirements of adaptive-optics wavefront sensors are also discussed. Only cursory attention is given to other relevant issues, such as readout speed and anti-blooming techniques.