If there is no buyers agent does the listing agent pocket all 6%?

[Manish A.]

I'm trying to understand exactly how agent commissions work.

Is this correct - When a seller lists a house, he comes to an agreement on commission with the listing agent and this is typically 6%?  What happens if he only wants to pay 4% or 2% total?

If the house is sold, and if there is no sellers agent, the listing agent keeps all 6%?  Or does the seller typically pay less commission when there is no buyers agent?

Thanks!