The researcher should be aware of archival terminology in order to get the most from your visit to an archive. The following definitions are from the Society of American Archivists:
Access--availability of historical materials through physical arrangement and intellectual guides
Acquisition--addition to the holdings of a repository of materials received by transfer, gift, bequest, purchase or deposit
Appraisal--the process of determining the value of records
Archivist--an educated, trained and experienced professional engaged in the management of archival and special collections materials
Arrangement--the pattern of organization of materials
Artifact--a 3 dimensional object showing human workmanship
Description--providing intellectual access to records
Finding Aid--a tool that provides access to a collection of records
Preservation--the process involved in the stabilization and protection of documents against damage or deterioration and in the treatment of damaged or deteriorated documents
Provenance--the archival principle that records the different offices of origin and the chain of custody from the record creator to the archives
The shape of the archival record- what exists in archives, and what is omitted- is, itself, a historical text worthy of study. Collections may hold omissions, called "archival gaps," because of bias, lack of resources, or many other reasons. For example, archival collecting policies would frequently prioritize capturing records of business, government, and academia, particularly reflecting the activities of men in power. At various points in the late 20th century scholars and archivists pushed to expand collections to include materials reflecting the experiences of women, people of color, members of the LGBTQ+ community, immigrants, laborers, students, the disabled, and many other groups. Further, many archivists sought to locate and make accessible materials already in their own collections that reflected the experiences and perspectives of these groups (for example, by re-describing a collection of letters to make it searchable under a wife's name as well as her husband's).
Processing collections is a highly labor-intensive and interpretive process. Many collections arrive at an archives in disarray: boxes of papers or digital files in no order, or partially organized; materials afflicted with mold or water damage; and very frequently, materials whose content, authorship, context, or date of creation are unclear. Archivists do their best to organize the collection where necessary (or, when a collection is already organized upon arrival, we maintain this original order) to ensure researchers are able to locate and understand relevant materials. Keep in mind, too, that as this is a human process, biases creep in to the organization schemes and descriptive information provided, which can shape the way researchers receive, contextualize, and understand the collection. Archivists do their best to limit interpretive language in their collection descriptions in order to allow researchers to draw connections and conclusions on their own.
Maintaining collection materials, especially digital collections, is quite resource-intensive. Sometimes an archives will refuse a collection because it cannot support its upkeep. Sometimes, despite best efforts, materials become unusable because of technical issues. This can also lead to gaps in the historical record.
More recently, many in the archives community have shifted in favor of a community archives model, in which archivists help provide support, training, and sometimes resources to local community-based collections and defer to those records holders for describing the materials and providing context and meaning. Often, collections like these- with or without professional archivists as consultants or employees- may have very rich material but limited resources. This means that their content may be less visible: fewer items digitized, fewer finding aids or collection guides available on the web, perhaps an antiquated website if they have one at all.