A scroll is a long strip of paper, parchment, papyrus or a similar material used for writing, usually mounted on a pair of spindles for ease of handling. Scrolls could often be dozens of feet in length -- text was written in columns crossing the width of the scroll itself, allowing for more convenient reading.
Scrolls are more unwieldy than the codices that replaced them, and are a less efficient use of paper. Because of this, a single large document (the Bible, for example) would have required multiple scrolls to accommodate it. Each scroll in such a collection was referred to as a "book", from which we derive the the modern usage.
In the SCA, award documents are commonly referred to as "scrolls". These are too small to be considered period scrolls, not being mounted on spindles and being, at most, two or three feet in length. In period these would have more probably been referred to as rolls.
Awards accompanied by a scroll include
In general, the higher the award level, the more work goes into the scroll. Depending on your kingdom/region, and the level of the award, scrolls can vary from computer print-outs colored in with magic marker, to customized professional quality illumination. Occasionally, a scroll will take an unusual form, such as carving the scroll on a facsimilie runestone for someone with a Viking persona.