Thread is light wait process. multiple thread have multiple flow control.. the best example of the thread is operating system. thread is saving time. multiple thread means multiple thread execute in same time.
On executing an exe, a process will be created, process can have multiple threads.
Process will have its own address space, threads will share the address space created by the process.
Thread is a small piece of the code within the single process. So multithreading means more than one thread will be executed at a time withing the single process.