Pirates and privateers are often considered to be the same things, leading to the words being used interchangeably by some. Scholars argue that there is a clear distinction between pirates and privateers, however, despite the fact that the realities of their work were often identical. During the Age of Sail, opportunists could actually change from one to the other, and records exist of seamen who switched sides several times during their busy lives. A pirate commits robbery under no one's authority, while a privateer's acts are under the orders of a ruling nation.
A pirate, by definition, is one who robs people by sea. The word comes from a Greek term that loosely means to find luck on the ocean. Traditional pirates are often considered free agents, not beholden to any governing body or system. This freedom has led to their modern portrayal as rebels and independents, hero figures that have abandoned conformative systems. In actuality, pirates are criminals who will often resort to violence in order to rob ships or towns.
Pirates and privateers differ subtly in several ways but their main distinction is very clear. While a pirate robs under the authority of no one, a privateer's acts of robbery or violence are under the orders of a ruling nation. In the 16th to 19th centuries, the major ruling countries of the world all employed privateers, to bring home money and to curb illegal piracy.
Privateers were not always naval officers, but both pirates and privateers operated their own ships. Both pirates and privateers would attack ships and towns for plunder, but a privateer was supposed to do so only if the target belonged to a hostile nation. Sometimes, privateers out for personal gain endangered peace treaties between warring nations by continuing attacks. This may not always have occurred out of greed, as correspondence was much slower in that era and news of treaties may not have reached the eager privateers.
Some experts do consider pirates and privateers to be identical, as both followed the same job description. The British privateer Admiral Henry Morgan was considered more brutal than many contemporary pirates, and once ordered an entire Spanish city massacred and burnt to the ground after capturing it. His behavior violated peace negotiations and nearly brought Spain and England back to war, but the Admiral was never convicted of piracy, as he was acting in the name of the government.
During times of need, nations would sometimes offer pirate amnesty to operating pirates. For a price, the pirate could purchase letters of marque that would make him a privateer and save him from being preyed on by the nation's agents. After receiving the letters of marque, pirates became privateers and would conduct missions on the nation's behalf. Many pirates would later violate their status and attack neutral vessels or even those of their own nation, however, and governments would rescind their status.
Some pirates began life as naval officers or privateers before turning or being considered a pirate. William Kidd, an Irish privateer working for the British government, did not realize he was considered a pirate until he returned to his home port after a raid and being arrested for piracy. He was later hanged for piracy, despite his protests that he was a loyal privateer.
Pirates and privateers are inextricably linked by the violent methods they used to obtain treasure. By a literal definition, they are separated only by the letter that one possesses and the other does not. The ability to change from one to the other at the opportune moment does suggest that they were not truly separated at all, but merely titles distributed to anyone who committed violence on the seas.