World Beyblade Organization by Fighting Spirits Inc.

Hi 

I am new to Beyblade community, I keep hearing ppl day G1-G5 and stuff.. can I kindly know what does it mean or stand? Is it some kind of grade or something? Like G1 is the biggest stage of Beyblade competition or what does it means.. appreciate someone could explain

Dude I believe it means generation 1-5 which is just a saying on which beyblade it comes from when it evolves