(USR). A modem manufacturer in Skokie, Illinois.

Undetectable and Untraceable Fraud. A major issue for information technology is fraud made possible by technology and electronic transactions, especially crimes that leave no trace and no audit trail.

User Agent. An OSI application process that can represent a human user or an organization to the X.400 Message Handling System. The user agent creates, sends, and receives messages for the user.

Unsolicited Bulk Email. Unsolicited bulk email , or spam, is an attempt by a company to get others to pay for its advertising. The costs of this kind of email are paid not by the company but by the Internet service provider and ultimately by the end user. Spam is seldom used by reputable companies. Most bulk email consists of chain letters, pyramid schemes, MMF ("make money fast") schemes, advertisements for pornographic sites, offers of software for collecting email addresses and sending unsolicited commercial email, stock offers for unknown startup companies, etc.

Universal Character Set. A character set using 16-bit character codes, also called ISO 10646. UCS is a standard defined by the International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC), and allows 65,536 (or 256 x 256) characters instead of the 256 available in ASCII. If a printer has the UCS feature, it can use a larger range of characters. The 8-bit character sets ASCII and ISO Latin 1 are subsets within UCS.