One in which the data is physically stored in the order in which it was acquired. To retrieve any particular record, it is necessary to read through every record before it. If the record does not exist, this will not become clear until you read to the end of the file. New records can only be added at the end of the file. Deleted records will leave a gap which cannot be re-used, unless the file is completely recreated. Serial files are mostly associated with devices such as tape drives.