Virtual safety car
A virtual safety car neutralises a race without deploying a physical car, by requiring every driver to stay above a delta time set by race control.
Also called vsc
Introduced after Jules Bianchi's fatal accident at Suzuka in 2014, for hazards that need the field slowed but not bunched up.
The key difference from a full safety car is that gaps are preserved rather than erased — a leader keeps their advantage in seconds. A pit stop still costs much less time than normal, which is why a VSC can hand a cheap stop to whoever had not yet made one.