Laura makes a good point, though as often as I've used it I've never been subjected to a dispute but that does not mean it never happens.

More and more websites, and even services, are using PayPal these days. I can even make payments to my doctor's office online via PayPal if I like.

Obviously the more ubiquitous it becomes the more attractive a target it makes for scan artists and hackers... At one time it was simply the "payment" arm of eBay unless I am mistaken, but over the years it has become far more than that.