Hyper-Threading Technology is used by CPU Manufacturers to increase CPU Performance.
Basically, a Processor has several cores on it that help you perform the tasks. So, the more cores you have, the more tasks you can perform. A CPU can have 2, 4, 6, 8, and 10 cores.
However, Intel has introduced a new technology called Threading (aka Hyper-Threading Technology). Hyper-Threading doubles the cores in your CPU Virtually.
It means, that if you have a Dual-Core Processor, it will perform like a Quad-Core Processor by using Hyper-Threading.
How does Hyper-Threading work?
With the help of Hyper-Threading Technology, we can divide the cores virtually, so that the CPU treats them as extra cores. Intel introduced this technology first, but it is also used by AMD Processors these days.
Ex: Intel i5 9400F has 6 cores and 6 threads. So, The 6 cores are divided by 6 threads, which makes it act as a 12-core CPU. Similarly, Intel i7 9700K has 8 cores and 8 threads, which makes it perform like a 16-core processor.
Disadvantages of Hyper-Threading:
Hyper-Threading works well for smaller tasks like playing music, watching movies, copying files, etc. So, you won't see much difference in performance while playing Large Games, Rendering Graphics, or Editing Videos
An i5 processor with 6 cores and 6 threads can perform better than an i5 processor with just 6 cores and no threads. But, it cannot perform better than an i7 processor with 8 cores and no threads.