A common use for importing during a software implementation is to bring in existing chart of accounts, customer lists, or vendors from existing software.
Bringing in a vendor bill, such as a large Federal Express bill, to avoid large amounts of data entry.
Exporting is frequently used for uploading payroll information to outside payroll services.
Exporting can also be used to produce special reports in Excel and Crystal reporting, for example, that otherwise cannot be produce with standard accounting reports.