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AirPort: AirPort is Apple's name for the IEEE (Institute of Electrical and Electronic Engineers) 802.11 wireless networking standard. The original AirPort based on the 802.11b standard has a maximum transmission speed of 11 Mbps. The newer AirPort Extreme is based on the 802.11g standard and has a maximum speed of 54 Mbps.

Allocation Block: The space on a volume is allocated as a group of consecutive sectors called an allocation block.

Allocation File: This file in the volume structures keeps track of the blocks that are used and those that are free.

AltiVec is a technology built into most PowerPC processors that provides increased performance for certain types of high-bandwidth data processing functions.

Apple Sound Chip: The Apple Sound Chip, or ASC, is a custom manufactured sound chip made for Apple by Sony.

ASC: See Apple Sound Chip.

ASCII: American Standard Code for Information Interchange is a numeric ID assigned to every number, letter, or other symbol that enables different programs and different computers to consistently share information. The standard code consists of an 8-bit coded number.

Attributes File: This file in the volume structures tracks the attributes of a file — such as whether the file is locked or not.

Backup: A backup is an exact copy of computer information. In case the data loss or corruption, the original data can be retrieved from the backup.

Benchmark Test: This is a test used to evaluate the performance of computer software and hardware.

Bit: A bit is the smallest unit of information that can be stored by a computer. It is represented as a 0 or a 1

Booting: The term booting originated from bootstrap. It is the process by which the computer starts itself and reads the Operating System. When you boot the computer from a CD, you are starting and reading the Operating System from the CD.

Bundle Bit: A bundle bit is a resource located in most Macintosh applications. If active, it indicates that the file contains icon information.

Bus: A bus is the path that transmits information between and computer and connected devices. An example is the USB bus, which connects the computer to USB devices such as keyboards and mice.

Byte: A byte is a unit of information stored in the computer. A byte consists of eight bits. An ASCII character consists of one byte.

Cache: This is a high-speed intermediate buffer memory that lies between the processor and the main memory in the computer's memory hierarchy. It can reduce memory access time.

Catalog File: The catalog file is a part of the volume structures. It keeps track of the files and folders on a volume.

Central Processor Unit: The central processor unit (CPU) or main processor unit is a chip that maintains the processing and sequencing facilities for machine-related functions such as initial program booting and instruction execution.

Chip: A "chip," or integrated circuit, is a miniature electronic component with specialized functions within the computer.

Clump: The file system attempts to provide allocation blocks for a file in a fixed size group called a clump.

CRT: CRT is an acronym for cathode ray tube. It is the element that produces the image on most computer and television screens.

Device: A device is any piece of equipment that can be attached to a computer. These might include a monitor, disk drive, printer, etc. Devices are also known as peripherals.

DIMM: See Dual Inline Memory Module.

Directory: This is another term for the volume structures.

Disk (disc): A disk is a flat circular device for storing computer data. The data might be stored magnetically or optically. The most common disks are CD-ROM disks made of stiff, translucent plastic.

Disk Drive: A disk drive is a device for controlling and accessing data stored on a disk or disk stack.

Drive: A drive is a computer peripheral that stores data. It might use a tape cartridge, a disk, or other medium. A drive may be "read only," or "read/write."

Driver: A driver (or device driver) is software that lets a computer communicate with a device such as a printer, hard, drive, etc. When you purchase a new device, its driver is usually provided as part of the software that comes with it.

Dual Inline Memory Module: A DIMM, or Dual Inline Memory Module, is a memory unit used by the computer. It contains RAM (Read Only Memory) chips mounted on a small printed circuit board that plugs into DIMM slots making for easy installation and removal.

Ethernet: This is a popular networking protocol originally developed at Xerox. Standard ethernet communicates a 10 Mbps and fast ethernet communicates at 100 Mbps or 1 GB (gigabyte).

Extents File: This file in the volume structures contains the extents data for the volume. Extents are the separate components of a fragmented file.

File System: Every volume uses a file system to organize the information it stores. A file system keeps track of where files are located on the volume. The Macintosh typically uses either the HFS or HFS+ filing system.

FireWire: FireWire is Apple's name for the high speed IEEE 1394 bus standard. It can handle data rates of up to 400 Mbps and is commonly used to connect hard drives and video cameras to the Macintosh. The new FireWire 800 handles data rates of 800 Mbps.

Firmware: This is software that has been permanently recorded into ROM (Read Only Memory). It is a cross between hardware and software.

GB: See Gigabyte.

Gigabyte: A gigabyte consists of 1, 024 megabytes.

Head: A head is a mechanism that reads, writes, or erases data on a storage medium.

Head Crash: A Head Crash refers to contact between a read/write head and a floppy or hard disk surface. This usually results in damage to the disk surface and loss of data.

HFS: HFS stands for Hierarchical Filing System and is also known as Macintosh OS Standard Format. It is a method of formatting storage devices for Macintosh Computers.

HFS+: Macintosh OS extended format that supports more files and increases the efficiency of storage on larger drives.

I/O: This is an acronym for input/output.

Initialize: initialization is a process of preparing a storage medium to hold data. During initialization, the volume structures for a volume are created specifying locations for storing data. Initialization erases directory information. However, the data in files themselves may be left on the volume.

Journaling: Journaling is a feature available for HFS+ volumes under Mac OS X 2.2 and above. If journalling is enabled on a volume, then the file system maintains a transaction log of reads and writes. This makes the file system more robust and helps protect against data loss in the event of an unexpected shutdown.

Kb: Kilobit or 1024 bits

KB: Kilobyte or 1024 bytes

Kbps: Kilobits per second.

KBps: Kilobytes per second.