How is one watt related to joules per second?

In the International System of Units (SI), the watt is the unit of power defined as being equal to one joule of work performed per second.12

This relationship signifies that power measures the time rate at which energy is transferred or work is done. While a joule represents the capacity to perform work, a watt indicates how quickly that energy is being utilized or delivered. The unit is named in honor of the Scottish inventor James Watt, whose improvements to the steam engine were a defining development of the Industrial Revolution.213