When you type commands in a login shell (window/terminal) and see a response displayed, you are working interactively. This is the most common way of working. The main downsides are that one cannot disconnect while a process is running (it would get terminated) and if many users run many jobs interactively the computer might get "overworked", slowing down all processes. Therefore, it is sometimes more practical to send jobs in the background or to submit batch jobs.
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Background processes
Send a job/process in the background
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