What is Hagrid's job at Hogwarts?

The story behind the answer

Rubeus Hagrid’s official post at Hogwarts is Keeper of Keys and Grounds. He looks after the castle’s grounds and creatures, escorts first-years across the lake, and is trusted with the school’s keys—hence the title. He is not the Defense Against the Dark Arts professor, nor the Potions Master (that’s Snape at first), and he isn’t Head of Gryffindor House (Professor McGonagall holds that role).

Background: Expelled as a student over the Chamber of Secrets incident, Hagrid was allowed to stay by Dumbledore and became gamekeeper; his broken wand is hidden in his pink umbrella. In Harry’s third year he also teaches Care of Magical Creatures. Memory tip: picture Hagrid jangling a giant keyring while tending the Forbidden Forest—he “keeps” the keys and the grounds.