Smartwatches with Bluetooth

Bluetooth (all versions)

— the wireless technology is used for direct communication between different devices. Almost all modern wearable gadgets use Bluetooth to connect to a smartphone or tablet. It is convenient due to the absence of wires, provides a communication range of 10 to 100 m (depending on the version), and different generations of Bluetooth are quite compatible in functionality that is relevant for wearable devices. As for specific versions, the newest v4 and v5 are described in the corresponding help items, but here are the features of earlier standards:

-v2.0. A variant considered nowadays as "classic Bluetooth" — newer versions are v2.0 with various add-ons and additions. However, in its pure form, this version is used extremely rarely — mainly among inexpensive or frankly outdated gadgets.
-v3.0. A standard that combines the traditional features of version 2.0 with a high-speed add-on that facilitates the transfer of large amounts of data.