Formula One is all about speed - how fast the car is, how quick are the driver's reflexes and equally important to win any race is how fast is the pitstop team. F1 cars go upto insane speeds, they go through a lot. The cars need the tyres have to be changed and other adjustments have to be made during the race, and to do all of these things, the men responsible have to be quick, they have to take split second decision that affects the driver's performance on the track. On an average, pitstops take about 2.5 seconds and have also taken as little as 1.92 seconds (Williams' team in 2016). More than just changing tyres, the team has to have precision co-ordination.
The drivers receive most of the glory, but Formula One is a team sport. The actions of the pit stop team can crucially affect the overall performance. Timing is the nucleus of this process, wherein the tyres are changed and damaged parts are replaced within a matter of seconds.
The car is to drive in for a pit stop towards the 'lollypop man', named for the distinctive shape of the long ‘stop/ first gear’ sign he holds, after which the car is jacked up fro the front and back. Three men are required for changing one tyre within such short times - one responsible for removing and refitting the nut with a high-speed airgun, the other takes away the old tyre and another places a new one.
Another quick process is adjusting the wings at the front and back in order to increase or decrease the downforce. However, if there's damage to the bodywork, it would take longer than the average time.
The William's team was so fast, it's actually difficult to see what's exactly being done. Here's a bonus video of the Red Bull team's pit stop in slow motion:
Pit stops used to be chaotic and time taking in the 1970s, but as the technologies advanced, the time spent at pit stops was shortened. In the yesteryear, there was no car-to-pit communication, and hence a driver came in to make an unscheduled stop.
The age of the modern pit stop arrived when changes were made to the sporting regulations for the 1994 season to allow fuelling during the race. By the time refuelling was banned again at the end of 2009, a driver’s visit to the pits had become breathtaking in its speed and efficiency.