When we say a business has a good moat, we are saying that it has a high ability to protect its market share. An example of a company with a good moat would be a government company operating in a sector that is reserved for the government.
Trivia: The term originates from โmoats around castles,โ which are deep ditches either dry or filled with water that surround castles and are meant to be a protective barrier against intruders.