A technique for implementing virtual machine interpreters, introduced by J.R. Bell in 1973, where each op-code in the virtual machine instruction set is the address of some (lower level) code to perform the required operation. This kind of virtual machine can be implemented efficiently in machine code on most processors by simply performing an indirect jump to the address which is the next instruction.

Many Forth implementations use threaded code and nowadays some use the term "threading" for almost any technique used to implement Forth's virtual machine.

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["James R. Bell", "Threaded Code", CACM, 1973, 16, 6, pp 370-372].

["An Architectural Trail to Threaded Code Systems", Kogge, P. M., IEEE Computer, March 1982].