Quantum physics studies the characteristics of subatomic particles. These particles are things like electrons, protons, and neutrons. Quantum physics also describes the building blocks which make these particles like quarks and gluons. Quantum physics is the science of the very small that Newtonian physics fails to suitably describe. Below are a selection of sites that will help you understand this science better:

Quantum Physics
1st place Quantum Physics site by Jim Tucek. A great site to learn about Quantum Physics.

HyperPhysics Concepts
This is a great site by Carl Rod Nave that graphs out the relationship between different theories along with details of each theory. Easy to follow and very interesting.

Visual Quantum Mechanics
Instructional units that introduce quantum physics to high school and college students who do not have a background in modern physics or higher level math using interactive computer programs and digital multimedia in an activity based environment.

The Quantum World : Quantum Physics for Everyone by: Kenneth W. Ford
This book is pure pleasure. It reads a bit like an adventure story as the author explains how the concepts of the quantum theory were developed to make sense of experimental results in the subatomic realm. The author's engaging style makes quantum theory seem almost easy!