Also transistor-transistor logic . One of several types of IC (Integrated Circuit). TTL logic gates are found in most simple Dual In-line Package chips.
Other types include resistor-transistor logic (RTL), diode-transistor logic (DTL), emitter coupled logic (ECL).
TTL circuits were used in Texas Instruments' TTl74 IC series in 1962, and were used into the 90's, when the +5v rail proved too inefficient for modern computer systems. They are still used in simple, DIL chips for teaching/simple logic purposes.