Question

what is physical memory

Answer 1

physical memory is exacty that. Something that is physical is able to be held in your hand. It is not virtual or prentnd, but rather a real and tangeble thing. Memory, in the sense of computers, is an information storage system at its most basic. It stores 0 and 1, nothing else, in an addresable matrix that allows for easy retrieval and usually easy storage. Some memory is write once, but the most common type would be the Random Access Memory of a compter or phone that allows for storage and retrieval of the things running on it a that moment.

Answer 2

Virtual memory is usually a section of the hard drive that the kernel swaps in/out pages of memory when there's no more physical (core) memory. Swapping is regarded as being 1000 times slower than physical memory because disk access times are in microseconds and physical memory access times are in nanoseconds.