What is the difference between threads and processes? When should you use threads, and when processes?

Processes and threads are units of execution in an operating system, but they differ in several key aspects:

• Process — an isolated unit of execution with its own address space, resources (files, memory), and system descriptors. Processes do not share memory directly, which ensures security and stability, but inter-process communication (IPC) is more complex.

• Thread — a lightweight unit of execution within a process that shares memory and resources with other threads of the same process. Threads are easier to create and switch between but require synchronization for access to shared data.

When to use:

• Use processes when tasks need to be isolated from each other, for example, to enhance security or when working with different applications.

• Use threads when tasks are closely related and require shared access to data, for example, for parallel processing within a single application.

Example: a web server may use processes to isolate clients, and within each process, threads to handle requests concurrently.