Did you know that you can reach past website visitors and app users? Let's say you’re a travel brand. You can now reach people who have joined your rewards program as they plan their next trip. For example, when these rewards members search for “non-stop flights to new york” on Google.com, you can show relevant ads at the top of their search results on any device right when they’re looking to fly to New York. And when those members are watching their favorite videos on YouTube or catching up on Gmail, you can show ads that inspire them to plan their next trip. Behind the scenes, this works by adding people to a UserList.

Prior to v201509 there were four different types: