Active: Refers to the status of a window. The active window is the current window. All actions will affect that window.

Access Control Entry (ACE): A list of users allowed to access an object and what their right and abilities are. The ACE also includes what group the user belongs to.

Access Control List (ACL): A collection of access control entries.

Active Desktop: A Web page turned into a Desktop background.

Active Directory: A hierarchical directory service whose primary purpose is the efficient management of users, groups, and network resources.

Address: A full path to a Web page. Also called a URL.

Alignment: How a paragraph is positioned within the margins. Can be left, center, right, or full justified.

Applet: Mini-programs of limited function that are bundled together as part of Windows.

Application: A computer program designed for a specific purpose, such as WordPad.

ASCII: The basic set of 256 characters (letters, numbers, punctuation). Used in plain text files.

Attachment: Other files included with a sent e-mail message.

Authentication: Verifying the identity of a user and the protection of a transmitted message from accidental or malicious modification.

Auto Arrange: Locks the Desktop icons in the columns at the left of the Desktop. When Auto Arrange is turned on, users cannot move the icons.

Bitmapped graphic: A graphic made up of a single image. Elements cannot be selected or moved once added.

Bridge: A device that connects two networks together.

Browser: Software that can process and display Web pages.

Bullet: A graphical market used to set off a list item.

Cache: Temporary storage area on a computer where visited Web sites are stored.

Center justified: Text is aligned along the center of text column.

Certificate: A digital document that verifies that the public key contained in the certificate actually belongs to the entity named in the certificate.

Certificate Authority (CA): An entity that authenticates that a key is valid and belongs to a particular individual or enterprise.

Clean install: To install Windows XP Professional from scratch; clears all installed programs and data.

Click: To press the left button of the mouse once while over an object. Select the object.

Client: A machine that requests something from a server.

Client/Server network: A centralized from of networking where at least one computer is designated as a server, a central computer in the network. The other computers, called clients, come to this server for a variety of purposes, for example, to access information.

Clip: Term used by Windows Media Player to refer to a sound or video file.