What are "hyperthreading" and "virtual cores"?

Solution 1:

Hyperthreading is a hardware feature and is not portable to other CPUs. Hyperthreading is essentially a duplication of the architectural and state hardware that surrounds the actual central processing units on a processor core.

It makes a single core processor look like a dual-core processor so that the data processing parts of the processor can be used slightly more efficiently. It is not as good as having another full processor performance-wise, but it does make slightly better use of the processor when under heavy use.

See this picture for a vague example, and if you want to read more then there's a good article on PCStats: