What's the difference between a pirate, a privateer and a buccaneer?

A pirate attacks ships and steals from them on nobody's authority but his own. A privateer does something very similar, but with a licence: a commission of war from a government that lets him raid the ships of a named enemy. A buccaneer began as something else entirely, a hunter, and only later became a raider. So between a pirate and a privateer the real difference was mostly paper, and who stood to profit.

The paper was called a letter of marque. It was the privateer's proof that he was not a pirate, and it usually named one ship, its officers and a set period of time. When a privateer captured an enemy ship, it was sold under prize law, and the money was divided between the sponsors, the shipowners, the captain and the crew, with a share going to the sovereign who had issued the commission. For a king, this was a bargain: he got a fleet without paying for it.

Buccaneers get their name from a smoking frame called a boucan. They were landless hunters of wild boars and cattle on Hispaniola and Tortuga, who smoked the meat and sold it to the sea raiders who preyed on Spanish shipping. In time the name came to mean the raiders themselves. Seen from London, buccaneering was a cheap way to fight Spain, so the English crown licensed them with letters of marque in return for a share of the profits.

But the line was never as clean as it sounds. A privateer who kept raiding after his commission ran out, or after a peace treaty was signed, could be accused of piracy. One captain, Thomas Tew, was given a commission to sail against the French and ignored it, raiding Mughal shipping in the Red Sea instead. Historians note that in practice the difference between privateers and pirates was sometimes slight, even a matter of interpretation.