Threads are a common way of implementing MultiTasking within a single application. They have less memory requirements than Processes, but still significantly more than Tasklets.

Threads come in slightly different flavours and are somewhat machine-dependent. Running more than a few thousand threads will most often be too slow even on a modern computer. With Tasklets it is possible to run millions while switching much faster between them, too.

Python support for threads has its own difficulties; for instance, killing a running thread is generally not possible.