A machine is any mechanical device that transmits or modifies energy to perform or assist in the performance of tasks. It normally requires some energy source ("input") and accomplishes some sort of work.

The scientific definition of a machine (derived from the Latin machina, is any device that transmits or modifies energy. In common usage, the meaning is that of devices having parts that perform or assist in performing some work. Devices with no rigid moving parts can be considered tools.

A machine is anything that makes work easier.

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