Pirate, privateer, corsair, buccaneer...all of these words can refer to a person who engages in high-seas thievery, but what's the difference? Here's a handy reference guide to clear things up.
PiratesPirates are men and women who attack ships or coastal towns in an attempt to rob them or capture prisoners for ransom. Essentially, they are thieves with a boat. Pirates do not discriminate when it comes to their victims: any nationality is fair game. They do not have the (overt) support of any legitimate nation and generally outlaws wherever they go. Because of the nature of their trade, pirates tend to use violence and intimidation more than regular thieves. Forget about the romantic pirates of the movies: pirates were (and are) ruthless men and women driven to piracy by need. Famous historical pirates include Blackbeard, "Black Bart" Roberts, Anne Bonny and Mary Read.
PrivateersPrivateers were men and ships in the semi-employ of a nation which was at war. Privateers were private ships encouraged to attack enemy ships, ports and interests. They had the official sanction and protection of the sponsoring nation and had to share a portion of the plunder. One of the most famous privateers was Captain Henry Morgan, who fought for England against Spain in the 1660's and 1670's. With a privateering commission, Morgan sacked several Spanish towns, including Portobello and Panama City. He shared his plunder with England and lived out his days in honor in Jamaica. A privateer like Morgan would never have attacked ships or ports belonging to another nation besides the one on his commission and would never have attacked any English interests under any circumstances: this is primarily what differentiates privateers from pirates.
BuccaneersThe Buccaneers were a specific group of privateers and pirates who were active in the late 1600's. The word comes from the French boucan, which was smoked meat made by hunters on Hispaniola out of the wild pigs and cattle there. These men set up a business of selling their smoked meat to passing ships, but soon realized that there was more money to be made in piracy. They were rugged, tough men who could survive hard conditions and shoot well with their rifles, and they soon became adept at waylaying passing ships. They became greatly in demand with French and English privateer ships, then fighting the Spanish. Buccaneers generally attacked towns from the sea and rarely engaged in open-water piracy. Many of the men who fought alongside Captain Henry Morgan were buccaneers. By 1700 or so their way of life was dying out and before long they were gone as a socio-ethnic group.
CorsairsCorsair is a word in English applied to foreign privateers, generally either Muslim or French. The Barbary pirates, Muslims who terrorized the Mediterranean from the fourteenth until the nineteenth centuries, were often referred to as "corsairs" because they did not attack Muslim ships and often sold prisoners into slavery. During the "Golden Age" of Piracy, French privateers were referred to as corsairs. It was a very negative term in English at the time: in 1668, Henry Morgan was deeply offended when a Spanish official called him a corsair (of course, he had just sacked the city of Portobello and was demanding a ransom for not burning it to the ground, so maybe the Spanish were offended, too).
Cawthorne, Nigel. A History of Pirates: Blood and Thunder on the High Seas. Edison: Chartwell Books, 2005.
Cordingly, David. Under the Black Flag New York: Random House Trade Paperbacks, 1996
Earle, Peter.The Sack of Panama New York: St. Martin's Press, 1981.
Konstam, Angus. The World Atlas of Pirates. Guilford: the Lyons Press, 2009