Thread basic

Application :

Application is a program which is designed to perform a specific task. For example, MS Word, Google Chrome, a video or audio player etc.

Process :

Process is an executing instance of an application. For example, when you double click MS Word icon in your computer, you start a process that will run this MS word application. Processes are heavy weight operations that they require their own separate memory address in operating system. Because of the processes are stored in separate memory, communication between processes (Inter Process Communication) takes time. Context switching from one process to another process is also expensive.

Thread :

Thread is a smallest executable unit of a process. Thread has it’s own path of execution in a process. For example, when you start MS word, operating system creates a process and start the execution of a primary thread of that process. A process can have multiple threads. Threads of the same process share the memory address of that process. i.e threads are stored inside the memory of a process. As the threads are stored in the same memory space, communication between threads (Inter Thread Communication) is fast. Context switching from one thread to another thread is also less expensive.