Which field (or fields) is used as a unique key during imports?

Match Fields is a generic term and not the specific ServiceNow terminology for identifying unique records during imports.

Coalesce fields are used during data imports to uniquely identify existing records in the target table, preventing duplicate entries. When a coalesce field is selected, ServiceNow tries to match the incoming data with existing records using that field; if a match is found, the existing record is updated, otherwise a new record is inserted.

Key Fields is a generic database term and not the specific ServiceNow terminology for identifying unique records during imports.

Sys IDs are unique identifiers for *all* records in ServiceNow, but during imports, you define which *source* fields should coalesce to an existing record, not explicitly using `sys_id` as the primary mechanism for matching external data unless the source data *is* `sys_id`.