The Elder Scrolls Construction Set allows you to edit and create any data for use with The Elder Scrolls IV: Oblivion. Any data that goes into the game goes in through the Construction Set and is stored in data files (labeled either ESM or ESP files) that are read by the game. The Construction Set allows you to create your own areas (towns, dungeons, islands, etc.) and populate them with characters, creatures, and stories. You can add new races, classes, spells, quests, potions, magic items, and anything else your mind can dream up.