Definitions: U

What is UCD?
UCD (User-Centered Design) is a method for designing ease-of-use into the total user experience with products.
What is a Unique?
A unique or unique visitor is the number of individual visitors with a unique IP address that visits a Web site during a specified period of time.
What is Unix?
Unix is a popular server operating system. Unix operating systems are widely used in servers, workstations, and mobile devices. The Unix environment and the client–server program model were essential elements in the development of the Internet and the reshaping of computing as centered in networks rather than in individual computers.
What is Uptime?
Uptime is the time during which a Web site or server is accessible.
What is a URL?
A URL (Uniform Resource Locator) is an address of a file accessible on the Internet.
What is URL Forwarding?
URL forwarding or redirection is the process of automatically forwarding or redirecting a user to a different file or web address, without the user's intervention.
What is Usability?
Usability is the user-friendliness and ease-of-use of a product to achieve specified goals.
What is a Usenet Newsgroup?
A Usenet newsgroup is a collection of user submitted messages and discussions on all kinds of topics that are posted to servers on a worldwide network.
What is a User Session?
A user session is each time a site visitor with a unique IP address enters a Web site during a specified period of time; usually 20-30 minutes, is counted as one user session. If the visitor exits the site and reenters within the specified period of time, it does not count as another user session.