MUMPS (usually written in capitals), or M, is a procedural programming language used to build applications that usually have large and/or complex databases. Its most important and defining trait is that language and database are very tightly bound. To programmers, the database seems to be a set of persistent, sparse arrays; called globals in MUMPS. All good MUMPS versions use sophisticated techniques to manage, cache, buffer, compress, and sort persistent data. These are normally intrinsic to the implementation and transparent to programmers. Originally interpreted, now, semi-compiled, and fully compiled versions exist. Most interpreted versions have very good runtime speed. It is a very productive developer environment due to: being interpreted, the flexible globals to which the language is closely bound, consistency of syntax, and compact representation.