Internet of Things (IoT)

Note the capitalization. Spell out on the first mention unless you're sure that your audience knows the term or IoT appears as part of a Microsoft product name. On subsequent mentions, use the abbreviation IoT.

Include the with the spelled-out term but not the acronym.

Examples
The Internet of Things (IoT) is reshaping every industry from manufacturing to medicine. And although IoT is a complicated endeavor, new innovations are making projects easier to deploy.
Learn how to use Microsoft Azure IoT Hub to connect, monitor, and control billions of Internet of Things assets.