FTTx (Fiber-to-the-x) is a generic term for any network architecture that uses optical fiber to replace all or part of the usual copper local loop used for telecommunications; it describes the fiber optic network for the "last mile" of the telecom connectivity between the communications provider and the customer.

The four technologies, in order of an increasingly longer fiber loop are:

• Fiber‐to‐the‐Node (FTTN) or Fiber‐to‐the‐Cabinet (FTTCab)
• Fiber‐to‐the‐Curb (FTTC),
• Fiber‐to‐the‐Building (FTTB)
• Fiber‐to‐the‐Home (FTTH) or Fiber-to-the-Premise (FTTP). Both are often used interchangeably.