This article lists concurrent andparallel programming languages, categorizing them by a definingparadigm. Concurrent and parallel programming languages involve multiple timelines. Such languages providesynchronization constructs whose behavior is defined by a parallelexecution model. Aconcurrent programming language is defined as one which uses the concept of simultaneously executing processes or threads of execution as a means of structuring a program. A parallel language is able to express programs that are executable on more than one processor. Both types are listed, as concurrency is a useful tool in expressing parallelism, but it is not necessary. In both cases, the features must be part of the language syntax and not an extension such as a library (libraries such as the posix-thread library implement a parallelexecution model but lack the syntax and grammar required to be a programming language).
The following categories aim to capture the main, defining feature of the languages contained, but they are not necessarily orthogonal.
These application programming interfaces support parallelism in host languages.