V8 Garbage Collection: Scavenge vs Mark-Sweep

V8 uses a generational GC: 'Scavenge' (Minor GC) for short-lived objects in New Space, and 'Mark-Sweep/Compact' (Major GC) for long-lived objects in Old Space.

Most objects die in New Space. V8 uses the Cheney algorithm to copy survivors. If an object survives multiple Minor GCs, it's promoted to Old Space. Major GC marks reachable objects, sweeps dead ones, and compacts memory.