Forth's niche was embedded control using small 8- and 16- bit computers with from 8 or 16 kilobytes up to 64 kilobytes of memory. Its heyday was the 1970s and 80s when those were the largest, most powerful computers that were economical for embedded control applications. As larger, more powerful computers with more elaborate software became affordable, Forth's niche shrunk away and the language became an obscure curiosity.

In its heyday Forth delivered impressive functionality on very small systems. You could have an interactive development system with a command interpreter, editor, assembler, compiler and the application on an 8 bit microcomputer with less, sometimes much less, than 64 kilobytes of memory.