Document date vs Posting date vs Entry date in SAP

Document date:

This date is manually entered at the time of data entry. This date can be in the past, current or future.

Purpose: This date is used for individual purposes. Normally it’s the date on physical copy of the supporting document e.g. vendor invoice

Posting date:

This date is manually entered at the time of data entry. It’s the date on which a document will be posted into the relevant posting period. The relevant posting period would need to be open for posting.

Purpose: Effect of document on the account books is provided on this date.

Entry date:

This date cannot be manually entered. System automatically picks the date of server as the entry date. This date can’t be changed.

Purpose: To know when was the document entered in sap.

Translation date:

By default system picks translation date same as posting date. But translation date can be changed manually while posting document.

Purpose: This date is used to convert foreign currency into local currency. Exchange rate between currencies is picked from exchange rate table depending upon this date.