Web 1.0 connected people to information and Web 2.0 connected people to each other, both iterations were built on technology and products governed by centralized organizations and corporations. Web 3.0 connects information, people, and property, essentially digitizing trust through decentralized blockchain technology.
One sentence? Here goes:
Web 3.0 is the latest iteration of the Internet, designed learning the lessons and incorporating the features from 1.0 and 2.0, into a decentralized trust network.