Courtly love was a special idea of love that people had in Europe in the Middle Ages. The word “court” in this sense means the courts where princes or dukes lived. Courtly love is usually when a young man, who may be a knight or even a simple musician, falls in love with a rich lady and tries to make himself of her by doing brave things or by singing beautiful love songs.
The idea of courtly love can be found in a lot of literature of that time, e.g. in works by Geoffrey Chaucer, Dante, Gottfried von Strassburg, Walther von der Vogelweide, Wolfram von Eschenbach, Malory and William Shakespeare.