Processes, in the context of Java application programming, are execution units in the operating system. When you start a program, you start a process. When the machine boots the code, the first thing it does is execute the boot process. This process then starts other processes that become the children of the boot process. These child processes may start other processes. This way, when the machine runs, there are trees of processes running.
When the machine does something, it is done in some code executing inside some process. The operating system also runs as several processes that execute simultaneously. Applications are executed as one or more processes. Most of the applications run as a single process but, as an example, the Chrome browser starts several processes to do all the rendering and network communication operations that collectively function as...