What should an administrator use as an identifier when importing and updating records from a separate system?

To use as an identifier when importing and updating records from a separate system, an

administrator should use External ID field type on an object. External ID fields allow storing unique

identifiers from external systems and using them for matching records during import or update

operations. External ID fields can also be used for upsert operations that insert new records or

update existing ones based on external ID values. For example, an administrator can create an

External ID field on Account object that stores account numbers from an external ERP system and use

it for importing or updating accounts from that system. Rich Text field, Record ID, and Auto-Number

field are not suitable for using as identifiers when importing and updating records from a separate

system. Reference:

https://help.salesforce.com/s/articleView?id=sf.fields_about_field_types.htm&type=5

https://help.salesforce.com/s/articleView?id=sf.data_loader_upsert.htm&type=5