I would assume that everyone has heard of PayPal. PayPal not only allows you to accept PayPal payments but they also process credit cards for your web site as well. Their credit card processing is pretty slick and you use your regular PayPal interface to manage your credit card transactions. Their rates are reasonable as well.
HOWEVER I recently dropped PayPal as a payment method for several reasons and the last incident was the final straw.
The last incident was that without warning they stopped accepting payments through my site by PayPal or credit card. Then they contacted me and told me some items on my web site were not acceptable by PayPal guidelines and PayPal could not be used to pay for them. First off, I sell NOTHING illegal, immoral or questionable. They made me remove close to 900 items from my web site before they would reinstate my services. What made matters worse was that even though it only took me an hour to fix my site it took them 4 days to review it and restart my service. Of course one it got restarted I removed PayPal as an option and put the items back in.
The other main issue I have with PayPal is that they offer zero to very little protection for the seller. They only way they will go to bat for you for is if you accept a PP payment and only ship it to the Confirmed address. Also, if you have a charge back situation the chances are VERY VERY slim that you will win if you are in the right.
Many of the customer support people rely on copy and pasting answers from the FAQ. Many of them really do not seem to understand your problem. I have often received answers that were not even related to my question.