Uber has become a massive global brand: It now operates with more than one million drivers in 400 cities across 70 countries. Being in so many places raises some well-documented obstacles when it comes to abiding by local regulations. But less visible are the challenges that come with trying to design an app interface that makes sense across so many different cultures. 

Speaking at the PSFK conference in New York City on Friday, Uber design director Ethan Eismann discussed some of the difficulties faced in designing the app to be compatible with riders and drivers everywhere.

1. Seventy countries means lots of languages--and varying levels of literacy.

One of the main reasons Uber eliminated the signature "U" in its logo--a decision that received plenty of criticism--is because the letter had no relevance in many of the countries where the company operates. But Uber's design challenges go even further: Many of its drivers have low levels of literacy--especially challenging since all training is done via the app. Because of this, the design team makes the onboarding materials as simple as possible: Drivers can get almost all the information they need by learning what the various symbols in the app mean, such as the heat map that uses color to show popular areas for pickups--red means an area is in high demand. And, since the symbols--and the interface as a whole--serve as the universal language among all drivers, Uber only makes adjustments to them when absolutely necessary.

2. Not all areas have enough internet access to support maps. 

While Americans are used to fast, 4G cell phone networks that can support the app's maps, much of the developing world uses 2G, which simply isn't fast enough. To keep the ride-hailing process a visual experience, the design team created a simplified version of the "arrival time" screen, which features a simple line segment that represents the total time it will take for the driver to reach the rider. The line becomes shorter as the driver gets closer, and important info like the driver's headshot, the car model, and the license plate number are all included on the screen.

3. If no maps wasn't hard enough--some regions don't even use addresses.

In parts of India, for example, users need alternative ways to communicate their locations to drivers. The Uber team added the ability for riders to take photos of their locations and send them to drivers. "Typically, the drivers know the city well enough to know what region or zone that rider is in," says Eismann, "and they can figure their way toward the location."

4. Certain cities restrict who can be on the road at certain times.

Cities like Beijing and Delhi restrict the roads to vehicles with license plates ending in odd or even numbers on certain days. The app added the carpooling option UberPool, which is embedded right in the main app and helps make more drivers available to riders at any given time, helping the company meet the demand caused by the restrictions. The option presents users with a map showing the best route to walk for an UberPool pickup. Developing features such as UberPool, Eismann says, was the result of hiring a design team that can see the bigger picture. "To design at Uber," he says, "you have to think about ethnography--the study of people in larger environments."