By the 11th century, a code of conduct for knights called chivalry had evolved. It was based on a combination of military ideals, Christian values, and etiquette. (The word comes from the French cheval, horse.) Chivalry required a knight to be bold, gallant, loyal, generous to a fallen foe, and reverent to God. A knight was supposed to protect the weak and respect women.

In practice, few knights lived up to the ideals of chivalry. Most knights paid little heed to the code when dealing with serfs and other persons not of noble birth, who were often victims of theft, brutality, and rape by knights. When dealing with noblemen and other knights, however, a knight generally abided by the standards required of chivalry.

The lives of the knights inspired a whole body of literature relating to chivalry. The literature included poems of courtly love written in France by minstrels (known as troubadours in southern France and trouvres in northern France). The literature also included many chansons de geste (songs of heroic actions), such as Chanson de Roland.

Minstrels would often tell romantic and heroic stories of the knight errant (from Old French errer, to travel), who rode through the land seeking chivalrous adventure, defending merchants from robbers, rescuing fair ladies, and helping the oppressed. Tales of the legendary or semilegendary past were popular, especially those relating to King Arthur and his Knights of the Round Table.

Chivalry reached its height in the 12th and 13th centuries. It became so elaborate and artificial that it was open to ridicule. Its exaggerations were satirized by Cervantes in Don Quixote (160515).