Arrangement & Description in an archives is similar to cataloging in a library. It means that the archivist is organizing and creating tools for users to know what is in the collection and how to find items within that collection.
Arrangement: n. ~ 1. The process of organizing materials with respect to their provenance and original order, to protect their context and to achieve physical or intellectual control over the materials. – 2. The organization and sequence of items within a collection.
In an archives the professional standard is to “respect original order.” This means that the archivist will maintain the way the person who created the collection organized it. Respect to original order presumes such an order is noticable. Archivists are not required to preserve ‘original chaos’, and may arrange such materials in a way that facilitates their use and management without violation of any archival principle.
Description: n. ~ 1. The process of creating a finding aid or other access tools that allow individuals to browse a surrogate of the collection to facilitate access and that improve security by creating a record of the collection and by minimizing the amount of handling of the original materials.
Archival description is similar to the process of description of books and some standards for archival description are derived from library standards. A key difference is that archival collections don’t have a title page, so the description comes from the context of the materials being described. Also, archival descriptions are intended to be updated if materials are added to the collection.Definitions from “A Glossary of Archival and Records Terminology” by the Society of American Archivists.