(1) To remove duplicate records from a file or to remove duplicate files in various storage locations. Deduplication "cleans" the data.
(2) A data compression method that stores only changes. For example, when a document is created, it is stored as a regular file. When changes are made, deduplication stores only the modified data in another file with indexes to the original. The changed locations may be identified by bytes or blocks. See
backup types.