A more thorough explanation:

A signature is a person's name or mark that they write themselves or ask someone else to write for them.

For example, when you sign a document, you are putting your signature on it. This could be your full name, your initials, or even a symbol that represents you.

Another example is when you receive a package and have to sign for it. The delivery person will ask you to put your signature on a device to confirm that you received the package.

These examples illustrate the definition of a signature because they both involve a person writing their name or mark to indicate their agreement or confirmation of something.