Hagrid's Hut is a wooden hut near the edge of the Forbidden Forest. Hagrid lives there, with his black boarhound Fang. Harry, Ron and Hermione frequently visit him, and they are often treated to Hagrid's home-made Rock Cakes which indeed seem to be made out of rock. He is a professor so it taken as one of the offices of professors in Hogwarts.
From the Story
"Hagrid lives in a wooden hut with his loyal boarhound, Fang, on the edge of the Forbidden Forest. The one-room home is cosy and warm, with a patchwork quilt on the huge bed, hams and pheasants hanging from the ceiling and a copper kettle over the open fire."