Melee is a type of combat, where there are a number of people engaged in hand to hand combat.
Melees in the SCA
In SCA tournaments, a melee is often a team combat (rather than every man for himself), and each side has their own objective, usually to completely eliminate the opposing side(s).
In this form of combat it is normal that a person may not kill from behind. However they may inform a person that they have been engaged from behind and that combatant should turn to meet that challenge. Melees generally do not allow the use of missile weapons, though there are some cases such as village football where this is allowed. Special scenarios are occasionally used, like ransom melees.
Melees can be fought either in the heavy or rapier lists. Wars are fought under different rules to melees so as to allow more weapons and greater scenarios.