A more thorough explanation:

Definition: An indorser is a person who transfers a negotiable instrument by endorsement. This means they sign the instrument to transfer ownership to someone else. An indorser is not the maker, drawer, or acceptor of the instrument.

Example: John writes a check to Sarah for $100. Sarah endorses the check by signing the back and gives it to Tom. Tom is now the indorsee (the person who receives the endorsed instrument) and John is the indorser (the person who signed the instrument to transfer ownership).

Another example: Mary is buying a car from Bob. She doesn't have all the money upfront, so she signs a promissory note to Bob for the remaining balance. Mary's friend, Jane, agrees to help her out and signs the promissory note as an accommodation indorser. This means Jane is acting as a surety for Mary and promises to pay the balance if Mary cannot.

These examples illustrate how an indorser transfers ownership of a negotiable instrument to someone else. In the first example, Sarah endorses the check to transfer ownership to Tom. In the second example, Jane signs the promissory note to help Mary out and promises to pay if Mary cannot.