A First Look at Some Key Concepts
kernel
The software component that controls the hardware directly, and implements the core privileged OS functions.
Modern hardware has features that allow the OS kernel to protect itself from untrusted user code.
thread
An executing stream of instructions and its CPU register context.
virtual address space
An execution context for thread(s) that provides an independent name space for addressing some or all of physical memory.
process
An execution of a program, consisting of a virtual address space, one or more threads, and some OS kernel state.