High-speed transceiver logic or HSTL is a technology-independent standard for signaling between integrated circuits. The nominal signaling range is 0 V to 1.5 V, though variations are allowed, and signals may be single-ended or differential. It is designed for operation beyond 180 MHz.

The following classes are defined by standard EIA/JESD8-6 from EIA/JEDEC:
*Class I (unterminated,