Hardware design languages (HDLs) allow computer hardware to be described in sufficient detail to be simulated and built, such a description being at a sufficiently high level of abstraction to make the complete design readily intelligible to anyone skilled in that language. A number of HDLs have been developed and are in use in IBM. To date, no overwhelming case can be made for choosing any one HDL over the others. The major trends in HDL are discussed. Several examples of HDLs are presented in some detail. VHDL, the yet-to-be released HDL which is to serve as a front end to the U.S. Government's Very High Speed Integrated Circuits program, is among these.