How threads differ from processes

Threads differ from traditional multitasking operating system processes in that:

processes are typically independent, while threads exist as subsets of a process
processes carry considerably more state information than threads, whereas multiple threads within a process share process state as well as memory and other resources
processes have separate address spaces, whereas threads share their address space
processes interact only through system-provided inter-process communication mechanisms
Context switching between threads in the same process is typically faster than context switching between processes.