Nano Technology is the Exponential Technology of the really small, about 1 to 100 nanometers. There is disagreement regarding whether the atomic level is the place to be, or just really, really small. Either way, the manipulation of matter on an atomic or molecular scale was first used for fabrication.
To get a feel for what Nano Technology is doing here is a short video:
Like much of the new technologies, there are a number of ways Nano Technology could change the world. The biggest ways this mini technology will impact us is likely just an insight away.
Much like Artificial Intelligence, there are a lot of really smart people that are warning about the pitfalls of such technology. It is reasonable to worry about Nano Technology as it is the manipulation of the small, but its reach would be globally felt, with or without that intention.
The benefits though are tremendous and can solve some of our biggest problems. Take a look at this video from Lockheed Martin: