What is an audit trail?

An audit trail is a software's change log. It automatically records who changed which value and when, what the old and new values are, and why. No one can edit it afterwards. EU GMP Annex 11 expects an audit trail for all data that matters for the quality of medicines, and through the Good Distribution Practice (GDP) guidelines this also applies in wholesale. You must review it regularly. In an inspection, the audit trail proves that no one has changed stock, batches or releases unnoticed.

Source: EU GMP Guide, Annex 11: Computerised Systems (European Commission)