What is hyperthreading?

In very simple turns, its something the CPU does to help run multiple thing at once.

Hyperthreading is basically multitasking for a processor. A hyperthreading processor will be able to handle 2 threads of activity at a time as opposed to a non hyperthreading processor which won't. The end result is more processing throughput per clockcycle than a non HT one and therefore more speed is observed. Your operating system will play a big part in this as well. If you go for a HT i7 you would be better off with a 64 bit OS which will handle the threads and cores more efficiently.

Define Hyperthreading

Define Hyper Threading

A technology developed by Intel that enables multithreaded software applications to execute threads in parallel on a single multi-core processor instead of processing threads in a linear fashion. Older systems took advantage of dual-processing threading in software by splitting instructions into multiple streams so that more than one processor could act upon them at once.

Everything you need to know about it.