摘要: To some extent, all Galactic binary systems hosting a compact object are potential `microquasars', so much as galactic nuclei may have been quasars, once upon time. The necessary ingredients for of stellar mass to qualify microquasar seem be: accretion, rotation and magnetic field. presence black hole help, but is not strictly required, since neutron star X-ray binaries dwarf novae can be powerful jet sources well. above issues broadly discussed throughout this Chapter, with rather trivial question in mind: why do we care? In other words: jets negligible phenomenon terms accretion power, or they contribute significantly dissipating gravitational energy? How influence their surroundings? latter point especially relevant broader context, there mounting evidence that outflows powered by super-massive holes external galaxies play crucial role regulating the evolution cosmic structures. Microquasars also thought form quasars impatient: what makes them appealing, despite low number statistics respect fast variability time-scales. first approximation, physics jet-accretion coupling innermost regions should set mass/size accretor: objects vary on 10^5-10^8 times shorter time-scales, making it possible study variable modes related ejection phenomena over average Ph.D. [Abridged]