Used for additional verification in formal documents or contracts. Your passport application will need to be countersigned by an eligible person.
Pro Tip 2/3
Higher Authority
A higher-ranking person or authority usually performs the countersigning as a form of endorsement. The director countersigned the junior manager's report to approve it.
Pro Tip 3/3
Dual Approval
Implies that two parties agree to the terms, with the second signature ensuring accountability. The contract won't be valid until you countersign it.