DRM (digital rights management) is the system that keeps premium content from being copied by encrypting the stream and tightly controlling who can decrypt it, when, and on what device. Encryption alone is not DRM — the hard part is secure key delivery and policy enforcement inside a trusted environment on the client, so the decryption key never sits in the clear where software can grab it.
A DRM-protected flow works like this: segments are encrypted (via Common Encryption) at packaging; when an authorized player wants to play, it requests a license from a license server; the server checks entitlement and returns the key plus a usage policy (output protection, expiry, offline rules) into a hardware-backed secure decryption module; only then does playback proceed.
DRM is usually a contractual requirement from studios, not an optional feature — for high-value content (new releases, 4K/HDR) studios mandate hardware-level protection. Because each platform ecosystem uses its own DRM, real services need multi-DRM.
