What is the Large Hadron Collider?

It's the biggest particle accelerator in the world at present. What it does is accelerate sub-atomic particles, usually protons, to near the speed of light and then collide them. The huge amount of kinetic energy is released as a series of secondary particles which are identified by particle detectors, the ferris wheel looking thing according to your article. This, in turn, helps us to better understand matter and energy on the sub-atomic scale.