The 7400 series of transistor-transistor logic (TTL) integrated circuits are historically important as the first widespread family of TTL integrated circuit logic. It was used to build the mini and mainframe computers of the 1960s and 1970s. Several generations of pin-compatible descendants of the original family have since become de-facto standard electronic components.

The 7400 series contains hundreds of devices that provide everything from basic logic gates, flip-flops, and counters, to special purpose bus transceivers and Arithmetic Logic Units (ALU). Specific functions are described in a list of 7400 series integrated circuits.

Today, surface-mounted CMOS versions of the 7400 series are used in various applications in electronics and for glue logic in computers and industrial electronics. The original through-hole devices in dual in-line packages (DIP/DIL), which were the mainstay of the industry for many decades, are very useful for rapid breadboard-prototyping and education and so remain available from most manufacturers. The fastest types and very low voltage versions are typically surface-mount only, however.