Finding aids are the primary tool used to facilitate the discovery of information for archival collections. They describe the collection and usually list of the contents of the collection. Archives are arranged into series. Series are just groupings of similar materials.
Finding aids usually include these features:
Biographical/historical note: Gives you information on the creator of the collection. It usually will give the context around which the collection was created.
Scope and Content Note: Summary of the contents of the collection. It may give you a description of the series found within a collection and highlight some of the contents or tell you the limits of the collection. This summary will give you an idea on whether this collection will help you with your research.
Container List: Box and folder list of all of the contents of the collection. This will tell you the contents of boxes so you know which to request at the archives.