Definition: Data mapping is the work of matching elements in one data set to the corresponding elements in another, so data can be combined, migrated or compared. It shows which fields line up, which extend existing data and which are new.
So what? Mapping errors are a common cause of data defects in integrations and migrations. A clear map tells testers exactly which relationships to check and where mismatches are likely.
Examples: Matching a new source's payment types to existing transaction categories. Mapping new customer fields into an existing customer dimension in a data warehouse
