Since 2006, three free practice sessions (often abbreviated to FP1, FP2, and FP3) are held before the race. The first is typically held on Friday morning and the second on Friday afternoon, while the third session is typically on Saturday morning. From 2021, all sessions last for one hour; prior to this, the Friday sessions were 90 minutes in length and the Saturday session was one hour in length. In addition in 2021, cars are now put under parc fermé conditions after the third practice session instead of qualifying. Private tests are now heavily restricted, but a third driver (such as a reserve, test, or junior driver) is permitted to take part in the first Friday free practice session in the place of a regular driver. The second practice session for the Bahrain, Singapore and Abu Dhabi Grands Prix takes place in the evening, as these races are run at night. All practice sessions for the Las Vegas Grand Prix were held at night, with the first two on Thursday, the third and qualifying on Friday and the race held on Saturday.