A more thorough explanation:

A copyright legend is a notice that indicates that a work is protected by copyright. This notice is usually placed in each published copy of the work. The copyright notice takes the form of the symbol ©, followed by the year of publication and the name of the basic copyright owner.

For example, a copyright notice for a book published in 2021 by John Smith would look like this: © 2021 John Smith.

Although a copyright notice is not required for a copyright to be valid since March 1, 1989, it still provides certain procedural advantages. The phrase "all rights reserved" is usually no longer required.

Here is an example of a copyright notice:

© 2021 Jane Doe

This notice indicates that Jane Doe is the copyright owner of the work and that it is protected by copyright law.

Overall, a copyright legend is a way to inform others that a work is protected by copyright and who the copyright owner is.