A more thorough explanation:

An endorsement (indorsement) is a way of showing support for someone or something. This can be done by publicly stating your approval or by promoting their skills or abilities. For example, a celebrity might endorse a product by appearing in an advertisement for it.

Endorsement can also refer to the act of signing the back of a check or other financial document. This signature indicates that the person who wrote the check has given permission for it to be cashed or transferred to someone else.

• A famous athlete endorses a brand of sports equipment.
• A politician endorses a candidate for office.
• A business owner endorses a charity by making a donation.
• A person endorses a check by signing the back of it.

These examples illustrate how endorsement can take many different forms, from public statements of support to financial transactions. In each case, the act of endorsing is a way of showing approval or giving permission for something to happen.