An archive refers to a collection of historical records, and also refers to the location in which these records are kept.
Archives are made up of records (AKA primary source documents) which have been accumulated over the course of an individual or organization's lifetime. For example, the archives of an individual may contain letters, papers, photographs, computer files, scrapbooks, financial records, diaries or any other kind of documentary materials created or collected by the individual--regardless of media or format. The archives of an organization (such as a corporation or government), on the other hand, tend to contain different types of records, such as administrative files, business records, memos, official correspondence, meeting minutes, and so on.
In general, archives of any individual or organization consist of records which have been especially selected for permanent or long-term preservation, due to their enduring research value. Archival records are normally unpublished and almost always unique, unlike books or magazines, in which many identical copies exist. This means that archives (the places) are quite distinct from libraries with regard to their functions and organization, although archival collections can often be found within library buildings.