A thing is a device which is registered in Omnyvore. It can be literally anything: a car, a stove, or even a medical device.
A thing family identifies a unique type of thing by pinpointing common features such as the measurements collected or the channels used to communicate by their things.
Networks are disjoint sets of things which are grouped for some rationale. For example, cars could be divided into networks according to the geographical region in which they are located.
Omnyvore can be used by more than one organization at a time. An organization is a company or a group of people which registers things, specifies a thing family for these things and then (possibly) divides things into networks.