Ashley Madison is the go-to network for having affairs. On this platform, you'll find people in stable relationships who are seeking an adventure, as well as single people who simply want to meet someone new... even though this app was made famous for the former more than the latter.
Using Ashley Madison is as simple as using any other dating app, like Tinder or Badoo. All you have to do is create your user profile by adding as many photos or as much information as you want, then choosing the kind of person you're interested in.
As far as dating apps go, Ashley Madison comes with a bit of stigma. After all, the app garnered a lot of unwanted attention when its users' emails were leaked... which was especially scandalous considering it's an app that most people don't want to be recognized on.