Charge-coupled devices (c. c. d. )22 offer the possibility of performing electronic functions simply and inexpensively for a vast range of electronic hardware applications. They can be designed specifically for optical imaging, mass memory for storing digital signals and also analog signal processing; alternatively, combining two or three of these functions on a single integrated circuit is likely to create novel electronic systems solutions which, hitherto, could not be realized sensibly with alternative components. This article examines basic c. c. d. operating features and discusses their technology and its limitations. The design concepts central to the three main emerging application areas are discussed, and likely developments are reviewed with reference to specific c. c. d. designs. 11 refs.