I can't encapsulate the totality of quantum mechanics in one page, not even in one book. It's a humble attempt to motivate people to start talking about quantum mechanics. Nex time, I will give a brief introduction of Einstein's Relativity. Again, for the same cause.
(With 81 members, this room is so dead.)
Let's get back to quantum.

When a ball is thrown in the air, it's position as well as velocity at any later time can be known by simple application of newton's laws. Even before the ball is thrown , it's position can be predicted to an arbitrary accuracy at all later times. Such a ball is said to be obeying the DETERMINISTIC laws of CLASSICAL or Newtonian physics.

Now let's do a thought experiment: replace the ball with an electron. Let's throw an electron in the air and ask a simple question? Where is the electron after some time has elapsed? Can we predict where my electron will be, or the type of path it will take. The simple answer is NO. Electron rebells against Newton's laws and therefore, Classical mechanics falls short of answering this question. We need a new set of laws that can be applied to an electron. These new set of laws is exactly what we call Quantum Mechanics.
Notice we still can't PREDICT where the electron will be. We can only calculate the probability of the electron to be at some point. Hence, in leaping from Classical to Quantum physics, we have forsaken the idea of determinacy and embraced uncertainty.

(feel free to reprove)