A yacht is a sailing or power vessel used for pleasure, cruising, or racing. There is no standard definition, though the term generally applies to vessels with a cabin intended for overnight use. To be termed a yacht, as opposed to a boat, such a pleasure vessel is likely to be at least 33 feet (10 m) in length and may have been judged to have good aesthetic qualities.

The Commercial Yacht Code classifies yachts 79 ft (24 m) and over as large. Such yachts typically require a hired crew and have higher construction standards. Further classifications for large yachts are: commercial—carrying no more than 12 passengers, private—solely for the pleasure of the owner and guests, or by flag, the country under which it is registered. A superyacht (sometimes megayacht) generally refers to any yacht (sail or power) longer than 131 ft (40 m).

Racing yachts are designed to emphasize performance over comfort. Charter yachts are run as a business for profit. As of 2020 there were more than 15,000 yachts of sufficient size to require a professional crew.