Threads, no not the threads you use to stitch fabric together, but Hyper-threading technology that's used in a processor. You might have stumbled up the terminology when you read up the listed specs on a processor. The base clock speed, the number of cores and yes, threads. All determining factors on how well a processor performs. Let's focus on Hyper-threading because it's an integral feature within the processor, the focal topic of Explanation Needed.
So what exactly are Hyper-threading? Without getting to overly technical, as best I can I'll simplify it so you can grasp the whole concept of what this technology actually does, and it's key benefits.
Hyper-threading was first introduced by Intel as a way to bring on parallel computing to consumer desktop computers. The technology made its market debut in the year 2000 with the Pentium 4 single core CPU, though it was revolutionary at the time the processor had limited functionality, adding hyper-threading was an attempt to have the single core processor be multitasking capable, allowing each core to perform several tasks at once.
With Hyper-threading, one single physical CPU appears as two logical cores to an operating system. Though it's a single CPU, the technology basically tricks the operating system into thinking that there's actually two CPU per core. Even though the OS sees two CPU for each core, the actual CPU hardware in reality have a single set of execution per core. Trickery comes to play as the CPU pretends as if there's more cores than there really is. In essence, unique technology is being used to add speed to program execution. With Hyper-threading, you have two logical CPU cores sharing a physical executed resources. So in theory this speeds up the whole operation, if one virtual CPU is slowed down and waiting for instruction, the virtual CPU borrows executed resources. Hyper-threading aids in speeding up your entire system, still and all having more cores within a processor always supersedes Hyperthreading or threads, mainly because processor cores actually does the physical labor within the processor. Web browsing or a email software will not likely see the benefits.
With processors today having an exuberant amount of cores, Hyper-threading is seen as an added "bonus". In the past, Hyper threading only had a single core that guise as multiple cores. Today, even with your low end processors you'll always have multiple cores along with Hyper-threading. Performance wise, a CPU with multiple cores is better than having hyper threading technology.