Nearly every fact in a modern lawsuit was created by software, stored on a server owned by someone else, and is one retention policy away from being gone. This article explains how electronic discovery actually works: when the duty to preserve attaches, what a litigation hold must do, how documents move from a custodian's phone to a production set, and what happens when evidence disappears. It covers the 2015 amendment that replaced a chaotic body of spoliation law with a single federal standard, the proportionality limits that now govern scope, and the technology-assisted review methods that made million-document cases affordable. It explains the special problems created by messaging apps, disappearing messages, personal devices, and cloud collaboration tools. Readers finish knowing what to do in the first week, what a defensible process looks like, and which mistakes produce sanctions rather than arguments.