DRM: Always Online
Any DRM that requires player to be constantly connected to authentication servers to play, even for singleplayer and LAN games.
Alternate names: Always-On
Name variations: Always On, Constant internet connection
The first video game about DRM: Always Online was released on June 2009.
This only covers the requirement for the internet connection for purposes of DRM, not for save cloud, online leaderboards, or any other online services.
A commonly touted reason for the necessity of always online system is presence of cloud computing, though this is often not actually covered how it is actually necessary for anything compared to processing everything on client side or on dedicated player run servers.