What is the difference between a process and a thread within an operating system?

A process is an instance of a running program that has its own address space, allocated system resources (file descriptors, sockets, etc.), and at least one thread of execution. Processes are isolated from each other.

A thread (or thread of execution) is the smallest unit of execution that can be scheduled by the operating system. It exists within a process, sharing its address space and resources, but has its own call stack, instruction pointer, and registers.

Main differences:

Parameter	Process	Thread
Address space	Own	Shared with other threads of the process
Resource allocation	Requires OS infrastructure	Cheaper to create
Isolation	High, processes are isolated	Partial, threads can communicate directly
Context switch	Expensive, requires OS context switch	Cheaper
Termination	Terminating a process ends all its threads	Terminating one thread does not affect others