1. Financial reporting - assurance - audit.
In the context of financial reporting, attestation is an independent review and report on a financial report, or related related systems and controls.
Different types of attestations include full audits, but also more limited reviews and related reports.
2. Law - wills.
In law, an attestation is a formal written statement by a witness that a will or other legal document was signed in their presence by the testator or other primary signatory.
3. Formal statements.
Any formal statement of fact, usually in writing.