Can someone give me a short, condensed and easy to understand description of what the G20 summit is?

I do not enjoy politics. I stray away from them usually. However, since this G20 summit is taking place so close to me, and so many people I know are so angry about it, I’m thinking I should learn a thing or two.

Anyone wanna key me in as to what all the rage with this thing is? I get that it’s the leaders of the 20 richest countries, making decisions for the world as a whole? Right? I dunno. Help.