I found it interesting so I thought I would share for those who dont know this.............
A courtesan was originally a woman courtier, which means a person who attends the court of a monarch or other powerful person.[1] In feudal society, the court was the centre of government as well as the residence of the monarch, and social and political life were often completely mixed together. In Renaissance Europe, courtiers played an extremely important role in upper-class society. As it was customary during this time for royal couples to lead separate lives — commonly marrying simply to preserve bloodlines and to secure political alliances — men and women would often seek gratification and companionship from people living at court. In fact, the verb "to court" originally meant "to be or reside at court", and later came to mean "to behave as a courtier" and then "to pay amorous attention to somebody".[2] The most intimate companion of a ruler was called the favourite.
As a result, in Renaissance usage, the Italian word "cortigiana", feminine of "cortigiano" (courtier) came to refer to "the ruler's mistress", and then to a well-educated and independent woman of free morals, eventually a trained artisan of dance and singing, especially one associated with wealthy, powerful, or upper-class men who provided luxuries and status in exchange for companionship.[3] The word was borrowed by English from Italian through the French form "courtisane" during the 16th century, especially associated to the meaning of "court-mistress" and "prostitute".[1]
A male figure comparable to the courtesan was the Italian cicisbeo, the French chevalier servant, the Spanish cortejo or estrecho. It actually seems that the figure of the chevalier servant (French, lit. serving cavalier, lady's escort) of a married lady was quite common in Europe up to the 18th century.[4]
Today, the term courtesan has become a euphemism to designate an escort or a prostitute
Courtesans from non-wealthy backgrounds were expected to provide charming companionship for extended periods, no matter what their own feelings or commitments might have been at the time, and had to be prepared to do so on short notice. They were also subject to lower social status, and often religious disapproval, because of the perceived immoral aspects of their profession and their reliance upon courtisanerie as a primary source of income. In cases like this, a courtesan was solely dependent on her benefactor or benefactors financially, making her vulnerable, Cora Pearl is a good example.
Often, courtesans serving in this capacity began their career as a prostitute, or were passed from one benefactor to another, thereby resulting in them being viewed in society circles as lower than both their benefactor and those of wealth and power with whom they would socialize. Often, in instances of this sort, if the courtesan had satisfactorily served a benefactor, that benefactor would, when ending the affair, pass them on to another benefactor of wealth as a favor to the courtesan, or set them up in an arranged marriage to a semi-wealthy benefactor. In the event that the courtesan had angered or dissatisfied a benefactor, they would often find themselves cast out of wealthy circles, returning more often than not to street prostitution.
http://en.wikipedia.org/wiki/Courtesan