What is the difference between processes and threads in Linux?

A process is an independent program in execution with its own memory space, file descriptors, and system resources. Creating a new process (fork()) is expensive.

A thread is a unit of execution within a process. Threads within the same process share the same memory space and open file descriptors, making communication between them fast. Thread creation is lighter than process creation.

In Linux, threads are implemented as “lightweight processes” and managed with the clone() system call. Tools like htop can show threads per process.