transaction

I had a seller offering a domain with price $450 and he is suggesting me to open a secure escrow.com transaction. What is escrow and how does it work? I heard about escrow sometimes but never worked with this site before. I would like to hear your advice and experience. Many thanks!

I have a website that selling digital products online, I want to have lowest Paypal fees when someone paid me through Paypal to buy a product. My question is, what is the best way to have lowest PayPal fees?