A scroll is an object with a one time casting of a spell or spells. Once used the scroll is destroyed. Unlike normal castings a scroll casting doesn't require mana, this makes them ideal for xping, as it reduces the time needed for regening. Scrolls are also a great way to cast a spell your character doesn't know yet, this can help with some quests where knowing a certain spell is required for completion. Warriors and thieves may find scrolls particularly useful as they don't have their own spells. Scrolls are something that are often farmed because they don't use mana they can be useful in xping as characters don't have to stop for regening, meaning they can fight for longer.
There are a wide variety of scrolls in the game many can be brought or stolen from shopkeepers. To search for objects of type scrolls use the scroll search switch e.g. list search +scroll. Note the level of the object is often different to the level of the spells. There is currently no search switch to search for specific spells.