Simply watch on the map the location of your contact addresses.
Not their current running location, but their postal addresses instead (home, work...), that you entered in your contact book.

Simply to watch where family members and friends live, and where some colleagues work, useful especially if you have a lot of such contacts...
This app thus provides a visual mean which helps to plan some visits, or which helps with commercial prospect, for example.

Beyond of this, the contact list shows their photo in a rather big size.
From there, access a contact detail view, within the app itself, to place a call, to send a message, to get the way to their address...

Same features on Apple Watch as on iPhone, except for the contact groups and for the contact detail view, which are not available on the watch.

New features should be added later (such as pull to refresh, in the list view, starting with iOS 15).

Neither the addresses, nor the contacts nor any else data are gathered or stored on a server by the app.