Programming languages come in all shapes and sizes and some of them hardly seem like programming languages at all. Of course, that depends on what you count as a programming language; as far as I'm concerned, a programming language is a language for specifying computations. But that's pretty broad and maybe we should narrow our definition to include only languages used for specifying computations to machines, that is, languages for talking with computers. Remember, though, that programmers often communicate with one another by sharing code and the programming language used to write that code can significantly influence what can or can't be easily communicated.

C, Java and Scheme are so-called general-purpose, high-level programming languages. Plenty of other programming languages were designed to suit particular purposes, among them the languages built into mathematical programming packages like Maple, Matlab and Mathematica. There are also special-purpose languages called scripting languages built into most word-processing and desktop-publishing programs that make it easier to perform repetitious tasks like personalizing invitations or making formatting changes throughout a set of documents.

Lots of computer users find themselves constantly doing routine housecleaning tasks like identifying and removing old files and searching for documents containing specific pieces of information. Modern operating systems generally provide nice graphical user interfaces to make such house-cleaning easier, but many repetitive tasks are easy to specify but tedious to carry out with these fancy interfaces.