When someone does an endorsement, they are guaranteeing that the instrument is genuine and that they have received it legally. They also promise that if the instrument is dishonoured, they will pay the amount to any later holder who presents it properly.

When someone provides an endorsement, they are offering a form of guarantee or support. Here's what it typically means:
Signature on a Document: Signing a document, like a check or contract, authorizes its transfer or validates its terms.
Guaranteeing Payment: In financial contexts, endorsing a negotiable instrument (e.g., a check) means the endorser guarantees payment if the issuer defaults.

Supporting a Claim: Endorsements can also mean publicly supporting a person, product, or idea, lending credibility.

Modifying Insurance Policies: In insurance, an endorsement is an amendment that changes the terms of the policy.

Legal Transfer of Rights: Endorsement can legally transfer ownership or rights, such as in the case of negotiable instruments.

Bank's Assurance: A bank endorsement assures that the institution will honor a check or instrument if the customer defaults.

Public Approval: It can also mean giving public approval or support, often seen in celebrity endorsements of products.

In essence, endorsement involves providing assurance, support, or validation in various contexts.