Beacons is a mobile app which allows mobile users to track each other on a map, designed with two goals in mind: privacy and simplicity.
Suppose Bob and Helen want to meet somewhere and they also want to know where the other one is, at any moment. Bob will create a Beacons session and pass the session key to Helen by phone, SMS or e-mail. After Helen joins Bob's session, they will be able to track each other's position as they move.
A session can be joined by any number of participants, as long as they know the session key.
Beacons is not exchanging any personal data with the server. The session key is randomly generated for each new session and each participant uses either the default nickname or whatever he chooses. If someone deliberately decides to use his real name as nickname that's a personal choice. Only the session key, the nicknames and the geo coordinates are exchanged with the server.
Once a session's participants count reaches zero on the server, the session is automatically deleted. Sessions inactive for more than an hour are also deleted.
As any app using the GPS, once it starts tracking your position, Beacons has a quite important impact on the battery life.
Yes, Beacons needs an internet connection to communicate with the server and, unless it is used over a WiFi connection, it will affect your data plan. However, the amount of data transferred by Beacons should be rather small.