the device came in range. Another similar use is to track pets, objects (e.g. baggage) or people. The precision and range of BLE doesn't match GPS, but beacons are significantly less expensive. Several commercial and free solutions exist, which are based on proximity detection, not precise positioning. For example, Nivea launched the "kid-tracker" campaign in Brazil back in 2014. Beacon protocols iBeacon In mid-2013, Apple introduced iBeacons and experts wrote about how it is designed to help the retail industry by simplifying payments and enabling on-site offers. On December 6, 2013, Apple activated iBeacons across its 254 US retail stores. McDonald's has used the devices to give special offers to consumers in its fast-food stores. As of May 2014, different hardware iBeacons can be purchased for as little as $5 per device to more than $30 per device. Each of these different iBeacons have varying default settings for their default transmit power and iBeacon advertisement frequency. Some hardware iBeacons advertise at as low as 1 Hz while others can be as fast as 10 Hz. iBeacon technology is still in its infancy. AltBeacon AltBeacon is an open source alternative to iBeacon created by Radius Networks. URIBeacon URIBeacons are different from iBeacons and AltBeacons because rather than broadcasting an identifier, they send an URL which can be understood immediately. Eddystone Eddystone is Google's standard for Bluetooth beacons. It supports three types of packets, Eddystone-UID, Eddystone-URL, and Eddystone-TLM. Eddystone-UID functions in a very similar way to Apple's iBeacon, however, it supports additional telemetry data with Eddystone-TLM. The telemetry information is sent along with the UID data. The beacon information available includes battery voltage, beacon temperature, number of packets sent since last startup, and beacon uptime. Using Eddystone protocol, Google had built Google Nearby that allowed Android users to receive beacon notifications without an app. Comparable technologies Although the near-field communication (NFC) environment is very different and has many non-overlapping applications, it is still compared with iBeacons. NFC range is up to 20 cm (7.87 inches) but the optimal range is < 4 cm (1.57 inches). iBeacons have a significantly larger range. NFC can be either passive or active. When using passive mode, the power is sent from the reader device. Although Passif (bought by Apple Inc.) has worked on reducing the energy consumption, a battery pack is still needed inside iBeacon tags at this time. Most Android smart devices ship with both