Mechanical power is the amount of work done per unit of time. Power can be modeled as an energy flow, equivalent to the rate of change of the energy in a system, or the time rate of doing work.
Instantaneous electrical power is defined as the product of the potential difference across a component, and the current flowing through it. If the component is a resistor, then it can be defined as the square of the current flowing through the resistor, multiplied by the resistance.
In optics, the term power is defined as the ability of a lens or other optical device to focus light.
Why am I defining Power all of sudden? Well, in a very abstract sense this explains why powerful nations, powerful persons, and powerful programming platforms, are what they are!