Didi is a ride-sharing company in China, similar to Uber or Lyft here in the US. According to Apple CEO Tim Cook, the company made the investment in Didi to better understand the Chinese market following the recent drop in sales.
"We are making the investment for a number of strategic reasons, including a chance to learn more about certain segments of the China market," said Cook.
Reuters reports that the ride-sharing service handles more than 11 million rides per day over seas. This outweighs Uber which only handles 2 million rides per day domestically.
Apple's investment might help the company decide how to handle sales and marketing for the Apple Car. If the vehicle were to be complete autonomous, implementing the Apple Car into a self-driving taxi service with Didi would be huge.