Digital revolution: A set of significant changes brought about by computers and other digital devices during the
second half of the 20th century.
Digitization To convert non digital information or media to a digital format through the use of a scanner,
sampler, or other input device.
Data processing An input processing- output cycle that converts data into information.
Local software Computer applications that are installed on and run from a local device, usually a computer hard
Computer network A collection of computers and related devices, connected in a way that allows them to share
data, hardware, and software.
Internet The worldwide communication infrastructure that links computer networks using the TCP/IP protocol.
Web Short for World Wide Web; an Internet service that links documents and information from computers
located worldwide, using the HTTP protocol.
Cloud computing A type of computing in which local devices access applications that run on a remote server,
where data can also be stored.
Convergence In the context of technology, the melding of digital devices into a single platform that handles a
diverse array of digital content, such as cell phones that also play digital music and display digital video.
Social media Online Web sites and services, such as Facebook, Twitter, and LinkedIn, that help users create
content and share it with others.
Intellectual property A legal concept that refers to ownership of intangible information, such as ideas
Open source An approach to developing and licensing software in which source code remains public so it can be
improved and freely distributed.
Globalization A group of social, economic, political, and technological interdependencies linking people and
institutions from all areas of the world.
Digital divide A gap between those who have access to digital technologies and those who do not.
Computer A device that accepts input, processes data, stores data, and produces output according to a stored
Input As a noun, the information that is conveyed to a computer. As a verb, to enter data into a computer.
Output The results produced by a computer (for example, reports, graphs, and music).
CPU (central processing unit)The main processing circuitry within a computer or chip that contains the ALU,
control unit, and registers.
Microprocessor An integrated circuit that contains the circuitry for processing data. It is a single- chip version of
the central processing unit (CPU) found in all computers. Memory The computer circuitry that holds data waiting to be processed.
Storage The area in a computer where data is retained on a permanent basis
File A named collection of data(such as a computer program, document, or graphic) that exists on a storage
medium, such as a hard disk or CD
Computer program A detailed set of instructions that tells a computer how to solve a problem or carry out a
Software The instructions that direct a computer to perform a task, interact with a user, or process data.
Apps Short for applications; popularly used to refer to applications available for the iPhone, iPad, and other
System software Computer programs, such as an operating system or utility software that help the computer
carry out essential operating tasks.
Operating system The software that controls the computer’s use of its hardware resources, such as memory and
disk storage space. Also called OS.
Personal computer A microcomputer designed for use by an individual user for applications such as Web
browsing and word processing.
Workstation (1) A computer connected to a local area network. (2) A powerful desktop computer designed for
Videogame console A computer specifically designed for playing games using a television screen and game
Client A computer or software that requests information from another computer or server.
Download The process of transferring a copy of a file from a remote computer to a local computer’s storage
Mainframe computer A large, fast, and expensive computer generally used by businesses or government
agencies to provide centralized storage, processing, and management for large amounts of data.
Supercomputer The fastest and most expensive type of computer, capable of processing trillions of instructions
Handheld computer A small,portable device such as a smartphone or enhanced media player that allows users
to install apps and store data.
Data representation The use of electronic signals, marks, or binary digits to represent character, numeric, visual,
or audio data.
Digital data Text, numbers, graphics, or sound represented by discrete digits, such as 1s and 0s
Analog data Data that is measured or represented on a continuously varying scale, such as a dimmer switch or a
watch with a sweep second hand. Numeric data Numbers that represent quantities and can be used in arithmetic operations.
Binary number system A method for representing numbers using only two digits: 0 and 1. Contrast to the
decimal number system, which uses ten digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9.
Byte An 8-bit unit of data that represents a single character.
Kilobyte (KB) Approximately 1,000 bytes; exactly 1,024 bytes.
Megabyte (MB) Approximately 1 million bytes; exactly 1,048,576 bytes.
Gigabyte (GB) Approximately 1 billion bytes; exactly 1,024 megabytes (1,073,741,824 bytes).
Integrated circuit (IC) A thin slice of silicon crystal containing microscopic circuit elements such as transistors,
wires, capacitors, and resistors; also called chips and microchips.
System board The main circuit board in a computer that houses chips and other electronic components.
Programming language A set of keywords and grammar (syntax) that allows a programmer to write instructions
that a computer can execute.
Source code Computer instructions written in a highlevel language.
Compiler Software that translates a program written in a high-level language into lowlevel instructions before
the program is executed.
Object code The low-level instructions that result from compiling source code.
Instruction set The collection of instructions that a CPU is designed to process.
Machine language A low-level language written in binary code that the computer can execute directly.
Machine code Program instructions written in binary code that the computer can execute directly.
ALU (Arithmetic Logic Unit) The part of the CPU that performs arithmetic and logical operations on the numbers
stored in its registers.
Instruction cycle The steps followed by a computer to process a single instruction: fetch, interpret, execute,
then increment the instruction pointer.
Authentication protocol Passwords, user IDs, and biometric measures used to verify a person’s identity.
Biometrics The use of physical attributes, such as a fingerprint, to verify a person’s identity.
User ID A combination of letters and numbers that serves as a user’s “call sign” or identification. Also referred to
as a user name.
Identity theft An illegal practicein which a criminal obtains enough information to masquerade as someone.
Dictionary attack A method of discovering a password by trying every word in an electronic dictionary. Brute force attack A method of breaking encryption code by trying all possible encryption keys.
Sniffing In the context of computer hacking, a technique that uses packet sniffer software to capture packets as
they are sent over a network.
Phishing An e-mail based scam that’s designed to fool users into revealing confidential information.
Keylogger A program, sometimes part of a Trojan horse, that records a person’s keystrokes, saves them, and
then sends them to a system administrator or remote hacker.
CHAPTER 2 DEFINITON
Peripheral device A component or equipment, such as a printer, that expands a computer’s input, output, or
System unit The case or box that contains the computer’s power supply, storage devices, main circuit board,
processor, and memory.
Desktop computer A computer that is small enough to fit on a desk and built around a single microprocessor
Portable computer Any type of computer, such as a notebook computer, that runs on batteries and is designed
to be carried from one location to another; also called a mobile computer.
Notebook computer A small, lightweight, portable computer that usually runs on batteries. Sometimes called a
Netbook A scaled-down version of a standard clamshell- style notebook computer. Sometimes called a mini
PC platform A family of personal computers that use Windows software and contain Intel-compatible
Mac platform A family or category of Macintosh-compatible personal computers designed and manufactured by
Linux platform A computer that is running the Linux operating system.
Smartphone A cellular phone that has a high resolution color screen, a browser, and the ability to run apps.
Tablet computer A small, portable computer with a touch sensitive screen that can be used as a writing or
Microprocessor clock A timing signal that sets the pace for executing instructions in a microprocessor.
Gigahertz (GHz) A measure of frequency equivalent to 1 billion cycles per second. 67
Multi-core processor A microprocessor that contains circuitry for more than one processing unit.
Megahertz (MHz) A measure of frequency equivalent to 1 million cycles per second. 68
Volatile A term that describes data (usually in RAM) that can exist only with a constant supply of power. Dynamic RAM (DRAM) Random access memory that requires a power source to hold data; used as main
memory on most computers
Virtual memory A computer’s use of hard disk storage to simulate RAM.
ROM (read-only memory) Refers to one or more integrated circuits that contain permanent instructions that the
computer uses during the boot process.
ROM BIOS A small set of basic input/output system instructions stored in ROM.
EEPROM (electrically erasable programmable read-only memory) A type of non-volatile storage typically used in
personal computers to store boot and BIOS data.
Storage medium The physical material used to store computer data, such as a floppy disk, a hard disk, or a CD-
Storage device A mechanical apparatus that records data to and retrieves data from a storage medium.
Magnetic storage A technology for recording data onto disks or tape by magnetizing particles of an oxide-based
Hard disk drive A computer storage device that contains a large-capacity rigid storage surface sealed inside a
drive case. Typically used as the primary storage device in personal computers.
Hard disk platter The component of a hard disk drive on which data is stored. It is a flat, rigid disk made of
aluminum or glass and coated with a magnetic oxide.
Floppy disk A removable magnetic storage medium, typically 3.5" in size, with a capacity of 1.44 MB.
CD (compact disc) An optical storage medium used to store digital information. CD-ROMs are read only. CD-Rs
CD-RWs can be used to record data.
DVD (digital video disc or digital versatile disc) An optical storage medium similar in appearance and technology
to a CD but with higher storage capacity.
Blu-ray A high-capacity storage technology that stores up to 25 GB per layer on Blu-ray discs (BDs).
Optical storage A technology that records data as light and dark spots on a CD, DVD, or other optical media.
Pits Spots on a CD that are “burned” onto an optical storage medium to represent digital data.
Lands Non-pitted surface areas on a CD that represent digital data.
Read-only technology Storage media that can only be read from, but not recorded on.