What's a vCard?

A vCard is a file containing contact information for a person or organization. It is supported by most address-book applications, e-mail clients, and many mobile devices. If you download a vCard and double click it, it should open up in your default address-book application and ask if you want to import a new contact. Your address-book may even open as soon as you click the link.

To learn more about vCards, Wikipedia has an article on them.