What distinguishes a thread of execution from a separate process in an operating system?

The main difference between a thread and a process in an operating system lies in the level of isolation and resource sharing:

• Process — is an independent instance of a program with its own address space, resources (files, memory, etc.). Processes are isolated from each other, and inter-process communication (IPC) is required for data exchange.

• Thread — is a unit of execution within a process, which shares the same address space and resources with other threads of the same process. Threads are easier to create and switch between than processes, but require synchronization when accessing shared data.

Example:

• A web browser is a process.
• Each tab or task within the browser can run in a separate thread.

Thus, threads provide parallelism within a process, while processes provide isolation and security.