They repeatedly broadcast a small identifier. Nearby phones hear it, estimate signal strength, and let an app decide what that means.
A lighthouse repeats “I am here.” Ships see it and decide what to do.
A beacon repeats a Bluetooth advertisement. A phone receives it and an app interprets its identifier.
Sends a tiny message again and again
Hears, interprets, then acts
The beacon usually does not know who heard it. It broadcasts outward; it does not open a conversation with every phone.
A typical beacon message is closer to a repeatedly shouted name tag than a transferred webpage.
Important: the exact fields depend on the beacon format. The phone normally needs an app or operating-system rule that already knows what the identifier means.
Permissions, background limits, and operating-system policies can prevent scanning or notifications.
Phones measure received signal strength, called RSSI. A stronger signal often suggests “closer,” but walls, bodies, reflections, antenna direction, and radio noise all distort it.
Think in zones: immediate, near, far, or unknown. Treating RSSI as a ruler produces jumpy results.
Apps smooth multiple readings over time and design for broad proximity zones rather than centimeter precision.