vCard is a electronic business card that can be shared with hand held organizers, PIM's, phones, over the internet or as attachment to your emails to mention a few options. The vCard can hold a lot of information like logos, sounds, you work info and private info. What time zone you are in enabling the user to easy find out when you are available. 

The vCard V2.1 Specification from the Internet Mail Consortium is the current standard developed in close relations with manufacturers of above mentioned devices.