There is no single centralised collection of, or index to, records within the National Archives. Many of the records in the collection are not clearly identifiable as being about a particular subject. The information can range from record items containing incidental or passing references to a particular subject through to detailed case files about specific subjects. Other information might be contained in records on apparently unrelated subjects and will only be identified by checking the record itself. This is a characteristic of archival records everywhere, and it makes research based on archival sources an analytical and labour intensive process.
Archival research involves the study of unique, original documents.
Consequently, the storage areas of the Archives, unlike those of most libraries, may not be browsed by researchers wishing to identify records that might be relevant. This means that researchers are entirely reliant on indexes and guides to locate material of relevance to their research. The Archives' role is to assist researchers to understand and use the indexes and other reference tools. The Archives does not undertake detailed research on behalf of researchers, nor does it interpret the records. The databases , fact sheets and guides created and maintained by the Archives to help researchers identify relevant records are called finding aids.