Bluetooth - Wikipedia
https://en.wikipedia.org/wiki/Bluetooth
Bluetooth is a wireless technology standard used for exchanging data between fixed and mobile devices over short distances using UHF radio waves in the ISM bands, from 2.402 GHz to 2.480 GHz...
Bluetooth 4.0: What is it, and does it matter? - CNET
https://www.cnet.com/news/bluetooth-4-0-what-is-it-and-does-it-matter/
The recently announced iPhone 4S comes with Bluetooth 4.0, which is a first for mobile phones. What exactly does Bluetooth 4.0 mean, and what advantages does that give the iPhone?
Specifications | Bluetooth® Technology Website
https://www.bluetooth.com/specifications/specs/
Learn About Bluetooth. Bluetooth Radio Versions. Major Solution Areas. About Bluetooth Security. Reporting Security Vulnerabilities. Develop with Bluetooth.