Hello! State-of-the-art means it is the best of whatever it is. It is used quite often in advertising to tell people that the product or service being advertised is the best they could find and uses the best knowledge or technology there is.

"State of the art," means "everything that's well known to any good engineer." "Art" is used in an old-fashioned sense: the knowledge of how to do something useful. It is a phrase used in United States patent law. You can't patent anything obvious. You can't patent anything that is already part of the state of the art. To be patentable, an invention must advance the state of the art. Casually, and in advertising, "state of the art," sometimes hyphenated as "state-of-the-art," means a product that uses the best and most up-to-date technology. Example: In 1981, the PC clock speed of 4.77 MHz was state-of-the-art, the best that engineers knew how to do at the time. Today, PC clock speeds are almost a thousand times as fast. The invention of the jet engine by Frank Whittle was a major advance in the state of the art.