I agree that threads are probably the dominant form of concurrency in modern programming, but it&#x27;s a relatively recent phenomenon. In pre-2.4 Linux kernels, for example, the threading was inadequate (remember LinuxThreads?) and the dominant model was multiprocessing, as it was in most of Unix itself. There are plenty of servers that still fork by default (Apache).<p>I believe it was Windows that really popularised multithreading as a form of concurrent programming as process creation is so expensive on that platform. I recall Linus ranting against adding threading to the kernel on more than one occasion.