This work presents an updated digest of Multicore Optical Fibre (MOF) technology and applications. The digest bases mainly on our own technological experiments. Several technologies have been employed to manufacture multicore optical fibres. These are: multi-rod-in-tube (1) rod drilling (2), modified double crucible (3), multicrucible-zone diaphragm (MZD) (4) and mozaic-assembling (5). The following kinds of MOF have been pulled and tested: singlemode and multimode twin-core, double-core (with two different cores - so called hetero-core MOF), with cores arranged linearly and with cores axially symmetrical. Highly asymmetrical MOF are also subject of a separate part of this work. Basic parameters and waveguide properties of these MOF have been presented and debated. The pulled MOF have been used to manufacture several pieces of MOF microoptics like: single tapers, bi-tapers, multiple tapers, mixing-rods, attenuators, passive lossy insulators, unidirectional and nonreciprocal optical devices, directio-nal couplers, WDM muldex and a number of different fibreoptic sensors. The components have been used and tested in optical fibre information processing, telemetric and communication systems.