If you are talking about “mainstream” systems programming languages on popular operating systems, there are three main families of threads.
- POSIX-style threads, which generally run on Unix systems
- Microsoft-style threads, which generally run on Windows systems
- Java threads, which are specific to the Java language, but run on a variety of operating systems
Other software systems have their own ways of handling threads and concurrency. They are too numerous to cover, but here are a few links to the threading systems of popular cross-platform software systems.