This communication protocol is short range and is known to almost anyone. It is very important and expected to be the key for wearable products. Raspberry Pi Zero W support bluetooth and this is a great opportunity for you to create projects and be familiar with this protocol. The new protocol Bluetooth Low Energy (BLE) or Bluetooth Smart is a significant protocol for Internet of Things and even if it has similar range it was firstly designed offering reduced power consumption. To conclude with, when talking about IoT, it is all about energy consumption. Your Raspberry Pi Zero W may work forever if it is plugged in the home power source, but if you are using it for wearables such as a smart watch, then the power consumption matters a lot.

Bluetooth is working at the frequency of 2.4 GHz (ISM) with a range of 20-150m (BLE) and with data rates up to 1Mbps (Smart/BLE).