Hyper-Threading Technology (HTT) is an implementation of simultaneous multithreading technology by Intel in their microprocessor series. The technology improves processor performance under certain workloads by providing useful work for execution units that would otherwise be idle, for example during a cache miss. HTT improves processor utilization and application performance under specific workloads. There are also cases in which enabling HTT can degrade an applicaiton performance. For further information check the official Intel website.