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Backlight: A handheld PC may have a backlight for its display, like a mobile phone, so that you can read it in the dark.

Baud: Pronounced bawd, the number of signaling elements that occur each second. The term is named after J.M.E. Baudot, the inventor of the Baudot telegraph code. At slow speeds, only one bit of information (signaling element) is encoded in each electrical change. The baud, therefore, indicates the number of bits per second that are transmitted. For example, 300 baud means that 300 bits are transmitted each second (abbreviated 300 bps ). Assuming asynchronous communication, which requires 10 bits per character, this translates to 30 characters per second (cps). For slow rates (below 1,200 baud), you can divide the baud by 10 to see how many characters per second are sent. At higher speeds, it is possible to encode more than one bit in each electrical change. 4,800 baud may allow 9,600 bits to be sent each second. At high data transfer speeds, therefore, data transmission rates are usually expressed in bits per second (bps) rather than baud. For example, a 9,600 bps modem may operate at only 2,400 baud.

Bay: A cavity in a notebook used primarily for removable drives but also for accessories. A two-bay notebook has an internal bay for the hard drive and a second bay for a CD-ROM, DVD-ROM, or floppy disk drive, which typically can be replaced with a spare battery. A three-bay notebook also has a floppy disk drive built in. Some manufacturers use the term spindles, referring to the shafts on which the disks spin, so a two-spindle notebook has two drives and two drive bays.  

BIOS: Pronounced "bye-ose," an acronym for basic input/output system. The BIOS is built-in software that determines what a computer can do without accessing programs from a disk. On PCs, the BIOS contains all the code required to control the keyboard, display screen, disk drives, serial communications, and a number of miscellaneous functions. The BIOS is typically placed in a ROM chip that comes with the computer (it is often called a ROM BIOS). This ensures that the BIOS will always be available and will not be damaged by disk failures. It also makes it possible for a computer to boot itself. Because RAM is faster than ROM, though, many computer manufacturers design systems so that the BIOS is copied from ROM to RAM each time the computer is booted. This is known as shadowing. Many modern PCs have a flash BIOS, which means that the BIOS has been recorded on a flash memory chip, which can be updated if necessary. The PC BIOS is fairly standardized, so all PCs are similar at this level (although there are different BIOS versions). Additional DOS functions are usually added through software modules. This means you can upgrade to a newer version of DOS without changing the BIOS. PC BIOSes that can handle Plug-and-Play (PnP) devices are known as PnP BIOSes, or PnP-aware BIOSes. These BIOSes are always implemented with flash memory rather than ROM.

BIT: Binary digit, which is the smallest unit of data a computer can handle. Each bit has a value of 0 or 1 which the computer interprets as on or off. 8 bits make up 1 byte. Abbreviated to b in data transfer rates - eg 10 Kbps (10,000 bits per second).  

Bluetooth: An up-and-coming technology for wirelessly transferring data short distances (up to 30 feet) among notebooks, cell phones, Palm or Windows CE handhelds, and printers. It is built into a few current notebooks, including some HP, IBM, and Toshiba models, but it's not yet a stable standard for mainstream users. It is not a competitor to wireless Ethernet. A Bluetooth- enabled PC Card can be added to a notebook for about $100. A few systems offer it built-in.

BUS: The bus is a set of conductors that connect all of the functional units in a computer, as well as external memory, peripherals, or networks. Higher System Bus Speed enhances a computer's performance and speed.  

Byte: A bit is like an on off switch and is the smallest unit of information that can be stored by a computer. A byte is made of eight bits and can represent a single letter. A kilobyte is 1024 bytes: a few paragraphs. Ashort book would be around one megabyte (1024 kilobytes).