Fiber optic cable is composed of one or more transparent fibers enclosed in protective coverings and strength members. Cable types can include simplex, duplex, multifiber, patch cord, and bare fiber.  Simplex cables are fiber optic cable with a single optical fiber.  Duplex cables are fiber optic cable with two optical fibers.  Multifiber cable is a fiber optic cable with several optical fibers.  Patch cords are short lengths of fiber optic cable with connectors.  Bare fiber refers to a fiber optic core and cladding only.  Fiber types can be single mode or multimode.  Single mode describes a fiber with a small core, only a few times the wavelength of light transmitted, that only allows one mode of light to propagate. It is commonly used with laser sources for high speed, long distance links.  Multimode describes a fiber with core diameter much larger than the wavelength of light transmitted that allows many modes of light to propagate. Commonly used with LED sources for lower speed, short distance links.