"EAD is an XML standard for encoding archival finding aids that describe collections of manuscripts and other archival materials, including information about provenance, the types of materials included, biographical and contextual information about the people whose papers are included in the archive, the organization of the archive, and similar information. EAD has some conceptual similarities to the TEI, having been developed at around the same time by some of the same people: like TEI, it permits both formalized and unformalized ways of representing metadata, and it is a comparatively human-readable and human-writable language, compared with other standards such as METS." -- Definition taken from Encoding Guide for Early Printed Books published by Brown University Women Writers Project
There are two main sections to an EAD record, the Header and the Archival Description. The Header contains information about the finding aid itself like, title, author, publisher, language, and description rules used.
The Archival Description is the information about the collection itself.
An example of an EAD finding aid can be found here.
Definitions with "*" next to them were taken from EAD Best Practices at the Library of Congress
Additional information provide by Lindy Smith, Reference Archivist. Music Library and Bill Schurk Sound Archives
Header <eadheader>:
_______________________________________________________________________________
Finding aid author: <author>
_______________________________________________________________________________
Finding aid date: <date>
_______________________________________________________________________________
Archival Description <archdesc>*:
Title of the Unit (Collection): Title of materials being described, usually the collection title or title of highest level being described in the finding aid.
Tag: "<unittile>"
Label: Title
_______________________________________________________________________________
Date of the Unit (Both exact and inclusive)*: Dates of the materials comprising the collection; the dates may be given as inclusive, bulk, or both.
Tag: <unitdate>
Label: "Dates" ; Span Dates ; Bulk Dates
_______________________________________________________________________________
ID of the Unit (Identifier)*: Identifying number or alphanumeric string used for control or citation purposes. Supply according to divisional practices. When no such ID is appropriate, use this element to supply unique country and repository codes by means of attribute values; the element will have no other content.
Tag: <unitid>
Label: "Call No." ; "Collection No."
_______________________________________________________________________________
Subjects*: A term that identifies a topic associated with or covered by the described materials.
Tag: <subject>
_______________________________________________________________________________
Format*: A term that identifies the types of material being described.
Tag: <genreform>
_______________________________________________________________________________
Related materials*: Information about materials that are not physically or logically included in the material described in the finding aid but that may be of use.
Tag: <relatedmaterial>
_______________________________________________________________________________
Preferred citation*: Information about how users should describe the materials when referring to them in published credits.
Tag: <prefercite>
_______________________________________________________________________________
Box/folder inventory
Tag: <unititle> ; <unitdate> ; <container>
Origination*: The <origination> element names, in authorized form, the individual/s or organization/s responsible for the creation, accumulation, or assembly of the described materials before their incorporation into an archival repository. There will in almost all cases be an <origination> element, whether or not a cataloging record for the materials uses main entry as a personal or corporate name or enters under title with added entries for the originator/s.
Tag: <origination>
Label: "Creator" ; "Collector"
_______________________________________________________________________________
Physical Description*: Statement or series of statements of extent regarding holdings of the collection. LC Practice requires the inclusion of physical description information within the Collection Summary.
Tag: <physdesc>
Label: "Extent" ; "Physical Description"
_______________________________________________________________________________
Language of the Material*: Use the <langmaterial> element with its subelement/s <language> to indicate the language or languages of the material represented in the collection.
Tag: <langmaterial>
Label: Language
_______________________________________________________________________________
Repository*: The institution or agency responsible for providing intellectual access to the materials being described. At the Library of Congress, the repository usually will be the custodial unit or division where the material is available for use.
Tag: <repository>
Label: repository
_______________________________________________________________________________
Abstract*: A brief statement about the creator or collector and the scope of the materials.
Tag: <abstract>
Label: "Abstract" ; "Summary"
Note: Generic explanatory text. In Collection Summary, may be used to indicate that the materials described in the high-level <did> are a component of a larger body of materials not described by the finding aid.
Tag: <note>
Label: "Note"
Additional notes can include: scope/content: <scopecontent> ; biographical/historical <bioghist> ; access restrictions <accessrestrict> ; usage restrictions <userestrict> ; arrangement/series <arrangement>
_______________________________________________________________________________
Physical Location*: Information identifying the place where the described materials are stored. Do not confuse with <container> or <repository>. Use of this element is optional.
Tag: <physloc>
Label: "Location"
_______________________________________________________________________________
Digital Archival Object Group*: A wrapper element for two or more related digital archival objects which should be thought of as a group and share a common description. In the collection summary area, used for "image samplers," or other visual or multimedia overviews of the collection consisting of selected images or other digital versions of collection material.
Tag: <daogrp>
Label: Image sampler