What's the purpose of Co2?

I've been reading the FAQ's and it says I should put Co2 into the room what's the purpose of this and is it important? Thanks Also, does it really help the plants grow way faster...like what's the difference if there's no Co2 artificially added? Thanks

Plants consume co2 and give off oxygen. The opposite of animals. Normal air has about 300ppm co2, if you raise it to about 1300ppm the plants will grow faster.