A trademark assignment is a legal document that transfers ownership of a trademark from one entity to another. It includes information about the current owner of the trademark, the new owner, and the trademark itself. The document must be signed by both parties and notarized to be legally binding. A trademark assignment is necessary when a business is sold, merged, or changed ownership in any way. It ensures that the new owner has all legal rights to the trademark and can use it without fear of infringement.