Here is a copy of my explanation from the guide to buying and selling on the right hand panel and the Paypal link.
I have always found Paypal easy to use as both a seller and a customer of on-line stores. As a payment system it's popularity is growing day by day and is widely used on both larger forums, such as Boots, eBay, Etsy and DaWanda to smaller business websites. I would recommend Paypal as a quick and reliable banking system.
Paypal describe their service as (direct quote);
Founded in 1998, PayPal enables any business or consumer with an email address to securely, conveniently and cost-effectively send and receive payments online. Our network builds on the existing financial infrastructure of bank accounts and credit cards to create a global, real-time payment solution.
PayPal has quickly become the leading payment network for online auction websites, including eBay. With over 100 million account members worldwide PayPal is also being increasingly used at other e-commerce sites. Users can send payments for free via their PCs or web-enabled mobile phones.
On eBay, DaWanda and Etsy Paypal can easily be used to make immediate payment for purchases at the checkout. Paypal make the payment on your behalf either from funds you have in your Paypal on-line account (which takes 10 days to add from your bank account), or your credit card (Mastercard, Visa, Maestro, Amex, Switch, Solo, Delta or Visa Electron), or by echeque (if you have no funds in you Paypal on-line account then Paypal will withdraw the amount from your bank account in 10 days to pay for your items).
Equally you can also receive payment from buyers through the same methods and the monies will be stored in your on-line Paypal account. You can then transfer any money received to your personal bank account, but note charges may occur if you withdraw less than the limit (see your account for details - in Britain the limit is £50). You should also note as a Seller, that Paypal will charge a percentage per transaction. Details of these are available on the Paypal site.
All you need is a UK, most European or US bank account to open a Paypal account... I think there are plans to role this system out to other countries soon.
The link to Paypal is http://www.paypal.com/