With the release of Watch OS 2, third-party developers are unvieling watch app updates that include complication integration. Complications are the small piece of information, such as the current temperature or your activity progress, presented on a watch face without launching an application.
Prior to the release of Watch OS 2, complications were reserved for Apple’s own apps. Think stocks, weather and calendar. But as developers keep on releasing updated apps for Watch OS 2, Apple’s complications will quickly become outnumbered.
For example, The Dark Sky, a weather app that lets you when know when it is raining or snow is imminent, recently updated with a complication; as did American Airlines and Citymapper.
When an app update includes a watch complication, it’s added to the list of available complications automatically. You’ll still need to add it to your watch face, however.
You have access to check which apps offer a complication by launching Watch app on your iPhone, then tap on the new Complications category, you will see the list of apps that offer a complication. This is also where you’ll need to go in order to edit or remove complications from the list of options.
Either drag an app down to the bottom “Do Not Include” section, or tap on the red circle next to the app’s name. I’ve yet to figure out what reordering complications does in this section, as they’re in alphabetical order on your watch.