Once Sonic has the 7 Chaos Emeralds, he can harness the awesome power inside them to change into Super Sonic form.
At this Super form, Sonic can fly, becomes almost invincible, his power and abilities are enhanced to infinity and his speed match the speed of light. He must continue to collect Golden Rings for the duration of Super Sonic, otherwise he morphs back into normal Sonic after certain time and has to change into Super form again.
The emeralds can be charged of positive and negative energy.
The only thing that can negate the effects and stop the energy of the 7 Chaos Emeralds, is the Master Emerald.