The Internet of Things is a term for the next phase of the Internet. As there are only about 8 Billion people in the world and almost half of them are already connected to the Internet, that is no longer an Exponential Technology.
Now, the exponentiality of the Internet will come from Things being connected to people, algorithms, and other things. The number of devices is limitless and is well on its way. However, the number of devices today is accelerating into tomorrow and beyond.