Unlocking Charm

Alohomora is a spell that unlocks doors. There are door-locking spells against which Alohomora is not effective, however. There are conflicting episodes in Harry Potter and the Order of the Phoenix as to whether or not it is effective against Colloportus. The spell is first used in Philosopher's Stone, when Hermione Granger uses it on the door to the forbidden third-floor corridor.