Offering a chat service in your app is a way to bring users closer together, for a social app, but also to create a space to exchange, debate or even improve the internal service of a company, by allowing employees to contact each other for example.
With the user list, registered users can also consult a list and even a map view of it, to display the users who are closest to them. The chat is 1:1 and only text can be exchanged.
The chat is a central feature to build a real community. Companies or community apps are perfect for this feature, but also think about different ways to use it, for example to manage a client service, or to add a more friendly side to an event app.