Superconductivity is a macroscopic quantum phenomenon. Flux quantization and the Josephson effect are two physical phenomena which can best reflect the macroscopic quantum properties. Superconducting quantum interference device (SQUID) is one type of superconducting devices which uses these two characteristics. SQUID devices are widely used in the sensitive detection of magnetic signals. This paper briefly introduces the background and recent developments of low temperature superconductor and high temperature superconductor SQUID devices.