These are the 5 main ideas represented by quantum theory:
1. Energy is not continuous, but comes in small but discrete units.
2. The elementary particles behave both like particles and like waves.
3. The movement of these particles is inherently random.
4. It is physically impossible to know both the position and the momentum of a particle at the same time. The more precisely one is known, the less precise the measurement of the other is.
5. The atomic world is nothing like the world we live in.
This is taken off the web, however, I have read a few books on the subject and find it to be very intregueing.