The term archives can have many different connotations, and the word can be used to refer to several different concepts. Many use the word archives to refer to collections of documents that are old or of historical significance--regardless of organization--for example, the back issues of a periodical. The noun archive (without an –s) is commonly used to describe collections of backup data in computing.
Archives, as a place, are responsible for preserving the legacy of an organization, a company, a person, a family, etc. Archives, as a resource, provide access to primary and secondary materials that document the place they are preserving. Archives, as a service, ensure that future generations can continuously learn from the collective voices of our past.
Archival Research can be overwhelming for those just learning the process. Most archival terms and processed are standardized, so that any researcher can proficiently conduct their research. Below are some definitions used by archival institutions/repositories throughout the world.
Series - Documents arranged systematically or maintained as a unit because they relate to a particular function or subject, result from the same activity, have a particular form, or because of some other relationship arising out of their creation or, arising out of their receipt and use. Many series contain groups of related papers that can be grouped under sub-series.
File - An organized unit of documents, usually within a series, brought together because they relate to the same subject, activity, or transaction.
Item - An archival unit that can be distinguished from a group and that is complete in itself. Items are usually found within files.
The history of humanity is too detailed to simply have a singular "type" of archive. The Society of American Archivists provides a great explanation of the types of archive repositories open for research.
Special collections are institutions containing materials from individuals, families, and organizations deemed to have significant historical value. Topics collected in special collections vary widely, and include medicine, law, literature, fine art, and technology. Often a special collections repository will be a department within a library, holding the library's rarest or most valuable original manuscripts, books, and/or collections of local history for neighboring communities.
Examples: The Mecklenburg Historical Association
Examples: Levine Museum of the New South
Examples: Sisters of Mercy Heritage Center (Belmont, NC), United Methodist Church Archives, American Jewish Archives