The word "corsair" comes directly from the French word corsaire, itself borrowed from the Italian corsaro. This derives from the Latin cursus, meaning "course" (as in journey or expedition). The French word corsaire may also come as a mispronunciation of the Arabic word "qorṣaan"; the term pirate had been in use in French since the Middle Ages.
The corsairs were privateers working for the King of France attacking the ships of France’s enemies. In France they did not need to fear punishment for piracy—being hanged—as they were granted a licence as combatants, the Lettre de Marque or Lettre de Course, a document which legitimised their actions to the French justice system and which they hoped gave them the status of a war prisoner in case they were ever captured.
The corsair was ordered to attack only the ships of enemy countries, theoretically respecting those of neutral nations and his own nation's. If he did not respect this rule, he was then treated as a pirate and hanged. The corsairs' activities also provided the King with revenue as the licence required them to hand over a part of their booty to the King.
In common with privateers of other nationalities, however, they were often considered pirates by their foreign opponents, and might be hanged as pirates if captured by the foreigners they preyed on.
The "corsair" activities started in the Middle Ages the main goals really being to compensate for the economic problems in war periods; and the ship owners did not accept that the war was an obstacle to their trade. Jean de Châtillon, who was a bishop, in 1144 gave the town of Saint-Malo the status of rights of asylum which encouraged all manner of thieves and rogues to move there. Their motto was "Neither Breton, nor French, but from Saint-Malo am I!". Saint-Malo however, progressed and in 1308 the town was made into a free commune to encourage the commercial activities of craftsmen as well as merchants and ship owners. This did not really work out and later in 1395 the town became a free port. This situation continued until 1688.