Fiber optic connectors are used to connect optical fibers where connect/disconnect functionality is required. Due to possible polishing and fine-tuning during the manufacture of the optical connector, the connector is usually assembled to the fiber in the supplier's manufacturing facility. However, the assembly and polishing operations involved can be performed on-site, for example to terminate long-term operation at the patch panel.

Fiber optic connectors are used in telephone switches, in customer premises wiring and in external factory applications for connecting equipment and cables, or for cross-connecting cables.

Most fiber optic connectors are spring loaded, so when the connectors are mated, the fiber end faces are pressed together. The resulting glass-to-glass or plastic-to-plastic contact eliminates signal loss caused by air gaps between connected fibers.

The performance of fiber optic connectors can be quantified by insertion loss and return loss. The measurement of these parameters is now defined in IEC standard 61753-1. The standard gives 5 ratings for insertion loss from A (best) to D (worst) and M ratings for multimode. Another parameter is return loss, on a scale from 1 (best) to 5 (worst).

A variety of fiber optic connectors can be used, but SC and LC connectors are the most common connector types on the market. Typical connectors are rated for 500–1,000 mating cycles. The main difference between connector types is the size and method of mechanical connection. Typically, organizations will standardize on one type of connector based on the equipment they typically use.

In many data center applications, small form factor (such as LC) and multi-fiber (such as MTP/MPO) connectors have replaced larger legacy (such as SC), allowing more fiber ports per rack space.