If you’re new to Formula One, you’ve likely heard of something called DRS when watching a race — and if you’re not already familiar with the ins and outs of the series, it can be a difficult thing to intuit. That’s why today, we’re breaking down everything you need to know.

This post is a guest post from Nicole Sievers, co-founder of . You can find her on .

What Is DRS?

DRS stands for “drag reduction system,” and it does exactly what it says on the package: DRS is designed to reduce drag. Functionally, pushing the DRS button moves an adjustable flap on the rear wing of an F1 car to enable it to have a better opportunity to pass the car in front of it by providing better downforce. The FIA estimates that activating DRS offers drivers an advantage of 6.2 to 7.5 miles per hour over the car in front, which can help bridge the gap between cars.

The DRS system was introduced in 2011 as a way to combat the difficulty many drivers had passing cars in front.

Why Does F1 Have DRS?

Race cars create turbulent air — basically, they punch through the air and leave a chaotic mess behind them. Imagine a car driving down a gravel road. In front of the car, the air is clear and free of dust. But once the car drives over the gravel, it kicks up a bunch of dust and dirt into the air, where it swirls around. That’s an easy way to imagine the turbulent air caused by race cars — but the forces of that turbulent air are obviously much greater than those caused on a dirt road.

F1 machines are designed with balance and complex aerodynamics in mind, but turbulent air is unpredictable and often negatively impacts any driver following closely behind another. That buffeting air can prevent a car from moving any closer to the following car, while the car in front has the ease of clean air and can drive away from the competition. It’s the difference between running on a calm day and running directly into the wind during a storm; your pace is going to be much slower running into the wind.

So, F1 introduced DRS to enable one driver to get close to another — and, as a result, to offer more chances for overtaking on the track.

DRS Rules

DRS can only be activated during certain instances in a race. First, you have to be within a DRS zone (which I’ll talk about below). Second, the following car must be within one second of the car it intends to overtake to activate DRS. This gives the following car a little extra ease when it comes to cutting through the being churned up by the car in front.

There are also a few rules around when you’re not allowed to use DRS. So, if you’re the driver that’s defending against the following car, you can’t use DRS to get away from that car unless you’re also one second behind a different car. Race control can also deactivate the use of DRS in dangerous conditions, such as when it’s very rainy.

Drivers aren’t allowed to use DRS until two laps of green flag racing have passed, whether that’s the start, restart, or resumption of a race after a safety car. Basically, the cars are so close to each other at the start that just about everyone could use DRS, which would kind of nullify the purpose of the system.

How Are DRS Zones Determined?

Each track on the F1 calendar has at least one DRS zone, though some can have as many as three. These zones differ in length at each track, since they’re placed on long straights where turbulent air is at its worst.

DRS zones consist of two parts: a detection zone and an activation zone. At the detection zone, sensors calculate the distance between two cars to determine if the following driver is eligible to activate DRS. If they can, then the driver can press the DRS button in the activation zone. They then have to release the DRS button before arriving at the corner at the end of the straight — which is often where the following driver tries to make a pass.

How Effective Is DRS?

The impact of DRS varies between tracks depending on the length of the activation zone, the downforce of the circuit, and what the track is like immediately after the DRS zone.

At a low-downforce track like Monza, there’s not much drag to reduce, so you’re less likely to see tangible results there than at a track that features higher downforce. In addition, if the DRS activation zone is very short, drivers will have less time to make up the distance between themselves.

Whether or not DRS is a good thing often depends on who you ask. The system was designed in such a way that drivers can’t abuse it to make every pass, but some people still feel that it offers too much of an advantage to drivers by downplaying their skills. But in the modern era, it’s easy to see that many on-track overtakes have been done with the help of DRS.