DS0 - A 64 kbit/s unit of transmission bandwidth. A worldwide standard speed for digitizing one voice conversation, and more recently, for data transmission. Twenty-four DS0s (24x64 kbit/s) equal one DS1.
DS1 - A 1.544 Mbit/s unit of transmission bandwidth in North America, and a 2.048 Mbit/s unit of transmission elsewhere. A telephony term describing a 1.544 or 2.048 Mbit/s digital signal carried on a T1 facility.
DS1 Channel - For a T1, a 1.544 Mbps unit of transmission bandwidth in North America, and a 2.048 Mbps unit of transmission elsewhere. A telephony term describing a 1.544 or 2.048 Mbps digital signal carried on a T1 facility.
DS2 Channel - For a T1 line, a 6.312-Mbps channel that consists of four DS1 channels; for an E1 line, an 8.45-Mbps channel that consists of four DS1 channels.
DS3 Channel - A 44.736-Mbps line consisting of seven DS2 channels. A DS3 line is also called a T3 line.
dB - deciBel, defined as 10 multiplied by the logarithm of the ratio of two power levels.

Erbium - Doped Fiber Amplifier - Means of fiber optic amplification. The transmitted light signal is passed through a section of fiber doped with erbium, a rare earth element, and is amplified by a pump diode.

Ferrule - A component of a fiber optic connection that holds the fiber in place and aids in its alignment.
Fiber - In fiber optics terms, refers to fiber made of very pure glass.
Fiber Distributed Data Interface (FDDI) - FDDI is a proposed ANSI standard for a network architecture that uses high-speed fiber-optic lines and supports transmission rates of up to 100 Mbps.
Fiber In The Loop (FITL) - A system for delivering services to contiguous groups of residential and small business customers using fiber optic media in either all or a portion of the loop distribution network. FITL is an umbrella term that encompasses various systems, such as Fiber to the Curb and Fiber to the Home.
Fiber Length - The physical length of the fiber. This length can then be translated to optical loss.
Fiber Optics - A term that describes the technology used to transmit infrared and visible light frequencies through a hair-thin strand of glass fiber, with a laser or light-emitting diode. The glass fiber, also known as an optical fiber, is to light what copper wire is to electricity.