D

Data
raw facts that are collected.

Data communications
use of a computer-based system to transmit data electronically.

Data communications media
means of transmitting data such as wire pairs, coaxial cables, or microwave.

Data Flow Diagram (DFD)
easy-to-use and understand tool that identifies the path data takes through the system.

Data/information flow
overall process of movement of data through an information system.

Data mining
the process of analyzing data in a data warehouse by using special tools to find information useful for business decisions that might otherwise not be discovered.

Data warehouse
large collection of data from business operations, as well as from other sources, that is used for extensive analysis.

Database
a group of related files.

Database Management System (DBMS)
a system that manages the access to, use of, and storage of data.

Database software
software designed primarily for use with many types of data that need to be linked in a variety of ways at different times.

Decision support system (DSS) software
software that assists users with decisions in which some or all of the information needed is not known in advance (semistructured or instructional decisions).

Dedicated communications channel
service in which the connection from one piece of hardware to another is used only for that connection.

Demand chain
process of responding to customer demands for products and services.

Design
a development phase during which a plan is developed for implementing a new system.

Digital computer
hardware widely used for business activities and designed to use the digits 0 and 1 to store data and instructions.

Digital signal
a discrete or pulse-type signal.

Direct access storage device (DASD)
storage method available with disks in which data can be located by its address rather than sequentially.

Disaster recovery
a plan of action used when a major disaster occurs (such as a hurricane, earthquake, or tornado), ensuring that critical computer systems can be available for use as quickly as possible.

Disk drive
hardware that contains the technology for storing and accessing data on a disk.

Disk pack
multiple platters (disks) used for secondary storage in one system.

Documentation
Explanatory materials identifying how a system was developed and how to use it.

Domain name system (DNS)
system that manages the Internet host names so that no duplicates occur.

Domestic organization
business activities occur only within the organization's home country.

Dot pitch (dp)
measurement of distance between screen dots; a lower dot pitch provides a sharper image.