You give them a credit card number or the routing number from one of your checks... they deduct the funds from your checking account or your credit card... the money is then placed into a mutual fund. The mutual fund is NOT secure meaning you could loose every dime in your account if the stock market crashes, but it is very doubtful since the fund makes very safe investments such as bank notes, paper production, etc... you will almost definately turn over a profit while your money sits in your paypal account (usually 3-5%). At any time, you can send this money to someone else's paypal account by giving paypal the email address connected to the account. For instance if you want to send my company $100, go to "send funds" and enter in [email protected] as the email address and enter 100 as the amount to send... then press the button. The money comes either out of your checkign account or credit card. The money will then sit in my company's paypal account till I choose to withdraw it. I can either get paypal to send me a check in the mail (1-2 weeks) or electronically transfer it into my checking account.
And if you are asking because you are planning on using A PARTICULAR SOURCE THAT I WILL NOT NAME BECAUSE I DON'T WANT TO MAKE A SOURCE POST - search the posts before you make your purchase.