What is parc fermé in F1?

From qualifying until the race, the cars are locked: teams may repair them but may not change the set-up.

From qualifying until the race, the cars are locked: teams may repair them but may not change the set-up.

Why

Teams must race with the car they qualified with, so nobody builds a one-lap special for Saturday.

When

From the start of qualifying (on sprint weekends from Sprint Qualifying) until the race. Small changes, like front-wing angle and tyre pressures, are allowed.

Breaking it

A team that changes a part or the set-up must start that car from the pit lane.

Why do some cars start from the pit lane?

Often because the team changed the set-up or parts under parc fermé, for example after a crash in qualifying.