Challenges are focused efforts to generate content in a particular place or around a theme. We provide a bit of an incentive — a prize for the best guide, or a donation to a related cause to encourage participation, and then let the community go wild. All of our current and past challenges are listed on the challenge page which can be an interesting way to browse content on nextstop as well.
To be honest, we're still experimenting with the format a bit so expect to see some changes. We're excited about them as a way to tease out specialized content from the community and help good causes at the same time. If you have an idea for a challenge, let us know over on the forum.
The guide that has the most number of likes will often be chosen as the 1st place guide. There are certain cases when the guide with the most likes isn't chosen, however, such as when one of the guides was created by someone on the nextstop team or if the guide has already won a very similar challenge. We try to give new guides a leg up in challenges to discourage simply entering the same guide multiple times into similar challenges. That being said, in rare cases there are guides with fewer likes that are just plain awesome. In general, though, we try our best to let the community choose Challenge winners via likes.