A single recorded song is really two copyrighted works — the musical work (the composition of notes and lyrics) and the sound recording (the master that captures one performance) — and each is authored, owned, registered, and monetized on its own track. This guide explains how band members become equal co-owners as joint authors under 17 U.S.C. § 201(a), why session players and producers need work-for-hire-plus-assignment contracts, and how to register both copyrights through the eCO system using the single, standard, GRAM, and preregistration paths. It maps the statutory payoffs that reward early filing: the right to sue under § 411 after Fourth Estate v. Wall-Street.com, statutory damages and attorney's fees under § 412, and access to the Copyright Claims Board. It also covers split sheets and band agreements, the two royalty pipelines (PROs and the MLC for compositions, SoundExchange for masters), sampling and interpolation clearance under the Bridgeport/VMG Salsoul split, and how deposit-copy scope decided cases like Skidmore v. Led Zeppelin. A worked example and an action checklist tie the doctrine to practice.