What are ISA Fees?

[Cass Broadview]

What exactly are "International Service Assessment fees?" (ISA) I ordered some violin accessories online from a master violin maker in paris france, and i noticed an ISA fee on my credit card bill. Mastercard claims they do not charge card holders, or merchants this fee. But they do charge my bank this fee, and apparently the bank passed it on to me? I paid with US Dollars, they were sent US Dollars. Does this fee apply to Paypal as well?

[Wiz Feinberg]

This fee is imposed by your bank or card supplier, to cover additional processing fees incurred with verifying and clearing International purchases.