An attic is the area between the living space and the roof. Some attics provide good storage space; others aren't accessible or large enough for storage.
Other names for an attic are garret, loft or sky parlor.
Large, old houses sometimes have attics big enough for rooms and fun play space.
Some of the issues with using attic space are the accessibility, since some attics are only accessible by ladder, temperature control, since attics are often above and outside the well insulated part of the building, and safety. Safety concerns can come from a few different sources -- access, unfinished attics may have exposed nails or insulation, and some insulation is not very safe to touch or breath regularly.
- doityourself on attics includes articles on insulation, ventilation, drywalling, etc. for the attic
- HowStuffWorks on "How to Make Your Home Energy Efficient: Attic Sealing and Insulation"
- HowStuffWorks on "How to Design Children's Rooms: Changing Attics and Basements into Children's Rooms"