Is Unjust enrichment a cause of action or remedy?

"Unjust enrichment is not a cause of action, however, or even a remedy, but rather ' " 'a general principle, underlying various legal doctrines and remedies' " . . . . [Citation.] It is synonymous with restitution. [Citation.]' (Melchior v. New Line Productions, Inc. (2003) 106 Cal.App.4th 779, 793.) Unjust enrichment has also been characterized as describing ' "the result of a failure to make restitution . . . ." ' [Citations.]" (McBride v. Boughton (2004) 123 Cal.App.4th 379, 387 (McBride).)