NOOP is short for “No-Op”, which is short for “No Operation”. This is a special command that counts as a command in the system but it doesn’t do anything besides increment the counter of the number of commands received. Usually, you write your software so it displays an informational message about the App you sent the NOOP to. For instance, many Apps will return their version number in response to a NOOP command. It’s primarily used as a check that everything is working. It’s sometimes used to “wake up” a system and make sure it’s ready to run.