Abstract: A computer implemented method is provided for synchronizing a first database located on a first computer and a second database located on a second computer. At the first computer, it is determined whether a record of the first database has been changed or added since a previous synchronization, using a first history file located on the first computer comprising records representative of records of the first database at the completion of the previous synchronization. If the record of the first database has not been changed or added since the previous synchronization, the first computer sends the second computer information which the second computer uses to identify the record of the first database to be unchanged.