Attestation is the act of verifying and validating the authenticity of a document or agreement by witnessing its signing and then signing it to confirm that it was properly signed by those bound by its contents. Attestation is a legal acknowledgment of the authenticity of a document and a verification that proper processes were followed. The person verifying the authenticity or validity of something or someone is an attester. Attestation is often done in writing to certify the statements.

There are different types of attestation, including:

• Attestation clause: This is a clause that is typically appended to a will, often just below the place of the testators signature, in the statutory law of wills and trusts.
• Witness attestation: This happens when a person not involved in a transaction (a third party) "attests" or witnesses the two involved parties sign a document. The third party then signs a statement that he or she saw the two involved parties sign the document, and sometimes verifies the content itself.

Attestation is an important final step that helps establish the authenticity and validity of documents like wills, deeds, and powers of attorney before they can be formally executed. Attestation requires the signature of one or more witnesses who are of legal age and capacity. The purpose of attestation is to provide assurance and credibility by examining evidence to verify compliance with specific requirements. Attestation engagements are performed by licensed professionals known as attestors, who determine whether a firms financial statements, internal controls, compliance with laws or regulations, or other subject matters are fairly presented.