U.S. Copyright Office Date
This is the effective date of registration assigned by the U.S. Copyright Office.
It will show on the certificate of registration the U.S. Copyright Office sends once the application is approved, as well as in an online public record for the registration which can be viewed via the Office’s website.
U.S. Copyright Office Registration Number
The purpose of a copyright registration is to have a verified record of the date, owner, and content of a work. This protects the copyright owner in legal cases of plagiarism or infringement. The copyright registration number is assigned to a work by the U.S. Copyright Office after an application and fee are submitted.
The copyright registration number is a twelve-character string that typically begins with a two or three letter prefix, such as “PA” or “PAU.” Zeros should be inserted between the prefix and the numerical portion of the number so that the total number of characters is 12.
For example: TX0001234567
To find the copyright registration number for a work after 1978 or verify if a work is in the public domain, you can search the U.S. Copyright Office’s Public Catalog here. Information on works before 1978 can be found in the U.S. Copyright Office’s Public Records Reading Room here.