A thread is a virtual version of a CPU core. To create a thread, Intel CPUs use Hyper-Threading and AMD CPUs use simultaneous multithreading!
For example, AMD CPUs use four cores to provide eight threads, and most Intel CPUs use two cores to use Hyper-Threading to provide four threads. The number of hardware threads indicates how many software threads can be executed simultaneously on the CPU.
They are really invisible to users, the operating system decides that a certain software thread is running on a certain logical processor, and a corresponding hardware thread on a certain core executes that software thread under any operating system e.g. B. Windows, Linux, MAC OS etc.