According to the search results, Colloportus is a charm that locks doors magically so that the door cannot be opened manually. It is a defensive spell that can be used to magically enchant a door or lock. The spell is taught to students at Hogwarts School of Witchcraft and Wizardry during their first-year Charms class from The Standard Book of Spells, Grade 1. The counter-charm for this spell is the Unlocking Charm (Alohomora). The spell finds application primarily in the fifth Harry Potter book (Harry Potter and the Order of the Phoenix) in the battle in the Department of Mysteries.