Simultaneous multithreading, abbreviated as SMT, is the process of a CPU splitting each of its physical cores into virtual cores, which are known as threads. This is done in order to increase performance and allow each core to run two instruction streams at once.
Intel branded this process as hyper-threading, but hyper-threading is the same thing as simultaneous multithreading. For example, AMD CPUs with four cores use simultaneous multithreading to provide eight threads, and most Intel CPUs with two cores use hyper-threading to provide four threads.
This article is part of the Tom's Hardware Glossary.