C

case-sensitive

Means that it matters whether or not letters are capitalized. Passwords in Mac OS X are case-sensitive. In some instances, such as in the screensaver password window, the dialog box will tell you if the caps lock key is pressed, alleviating the frustration of being sure the correct password is being typed in but having it entered unknowingly in all caps.

character

A written representation of a letter, digit, or symbol. A single character could be the letter “W” or an exclamation point (!).

checkbox

Gives you the option of activating or deactivating a setting presented by the operating system or by a program. A checkbox is literally a box that has three different states, blank, checked, or dashed. A check indicates a setting is chosen, a blank means it has not been chosen, and a dash usually is presented if multiple items are selected with different settings (such as ownership and permissions of files viewed in the Finder) or to indicate that settings will not be changed. In the realm of mathematical logic, a series of checkboxes function as an “AND.” That is, out of five boxes, you can select one and two and three. Contrast this to the radio button.

clean installation

A type of Mac OS X installation in which a new, fresh copy of the system is installed, and the original system folder is left unaltered and moved into a “Previous Systems” folder at the root level of the hard drive. An option for preserving the user folders is available.

CLI

See command-line interface

click-and-a-half

A gesture used to make a disk or folder spring open. To perform the gesture, begin to double-click the disk or folder, but do not release the mouse button after the second click.

click-through

The ability to interact directly with an item in an inactive window. For example, you can operate the Close, Minimize, and Zoom buttons in most inactive Aqua windows.

client

A program (or a computer running a program) that requests and receives information or services from a server.

clipping file

A file created by the Finder to hold material that has been dragged from a document to the Desktop or a Finder window.

closed network

An AirPort network that requires you to type its name (not simply pick the name from a list) to connect to it.

Cocoa

Applications that are specifically developed for Mac OS X. Cocoa applications are incompatible with older Macintosh operating systems. Cocoa applications take advantage of all of Mac OS X’s modern OS features, such as advanced memory, preemptive multitasking, symmetric multiprocessing, and the Aqua interface.

codec (compressor-decompressor)

Something that compresses data so that it takes less space to store and decompresses compressed data back to its original form for playing or other use. A compressor may consist of software, hardware, or both.

collated

Multiple printed copies of a document with each copy having all its pages in the correct order.

color depth

The number of bits of information that are required to represent the number of colors available on the screen. For example, a screen that can display thousands of colors is set at a color depth of 16 bits. Compare to pixel depth.

Color picker

The dialog in which you specify a custom color either by clicking a color wheel, clicking a color sample, or entering color values.

command-line interface

A non-GUI method of interacting with the operating system. A means of interacting with and controlling a computer by typing commands into the terminal, one line at a time.

comment

An AppleScript line that begins with a hyphen, or a Unix command line that begins with a number sign character (#), which in either case means that the line is descriptive and not a command to be performed.

compile

To convert the human-readable text of an AppleScript script into command codes that a Mac can execute. As part of this process, AppleScript checks the script for nonconformance with AppleScript grammar, such as a missing parenthesis.

compression algorithm

A method for compressing data so that it fits in less space and can be transferred more quickly. Each compression algorithm generally works best with one type of data, such as sound, photographs, video or motion pictures, and computer-generated animation. Three characteristics of a compression algorithm determine how effectively it compresses — compression ratio, fidelity to the original data, and speed.

compression ratio

Indicates the amount of compression and is calculated by dividing the size of the original source data by the size of the compressed data. Larger compression ratios mean greater compression and generally (although not always) a loss of quality in the compressed data.

conditional

A programming command that evaluates a condition (stated as part of the conditional) to determine whether another command or set of commands should be performed. (Also referred to as a conditional statement.)

contextual menu

A contextual menu lists commands relevant to an item that you Control-click.

Control Panel

A small Classic application that you use to set the way some part of the Classic environment looks and behaves. Similar to OS X Preference panes.

cooperative multitasking

A scheme of multitasking used by Classic applications whereby multiple applications are open in the Classic environment and voluntarily taking turns using the Classic environment’s processing time. While each Classic application is idle, it allows other Classic applications to use the processor. Compare preemptive multitasking.

crack

A means of circumventing a programs serialization and security.

crop markers

Small triangles that indicate the beginning and end of a selected part of a movie in iMovie.

crossover cable

A cable whose wires are reversed inside the plug at one end of the cable.

custom installation

You can selectively install Mac OS X packages. You can also selectively install Mac OS 9 modules for the Classic environment.