Zwift is a turbo trainer game that enables you to link you turbo trainer up your computer, your iPad and iPhone, letting you ride with other cyclists in a virtual environment, therefore helping to alleviate some of the boredom associated with indoor riding. Zwift also says that the game can be better than outdoor riding, where “weather, traffic, time constraints and distance from other cyclists can take the fun out of it.”
There are two different courses on Zwift: Watopia and Richmond. While the Richmond course is a copy of the course from the 2016 Road World Championships, Watopia is a made up course which has been plonked down somewhere in the Solomon Islands according the Strava. Although there are numerous user-generated Strava segments, each course contains three different official segments, each shown by an arch over the course. The orange arch measures your overall lap time, the green arch measures your time over a short sprint, and the polka dot arch measures your time up a hill on each course.
Source (Cycling Today, “Everything you need to know about Zwift indoor cycling”)