Deflector shield

The Deflector shields (or more commonly referred to as shields) are an electromagnetic field that can be projected around a starship, starbase, or planet and act as the first form of defence against enemies or natural hazards.

While humans didn't develop shield technology until the late 22nd century, many species in the Alpha and Beta Quadrants had developed the technology by the 2150s, such as the Andorians and the Klingons. (ENT episodes: "Sleeping Dogs" and "Proving Ground").