Commerce in the physical world is called marketplace, while commerce in the information world is called ____________________.

___________ is an attachment to an e-mail message or program embedded in a Web page that verifies that the sender or Web site is who it claims to be.

A computer must have a(n) ____________________ to run programs.

____________________ valuations are amounts that bidders are willing to pay for an item.

In general, the creation of a separate experience for customers based on their behavior is called ____________________.