  Fast liquid jets, called micro-jets, are produced within cavitation bubbles
experiencing an aspherical collapse. Here we review micro-jets of different
origins, scales and appearances, and propose a unified framework to describe
their dynamics by using an anisotropy parameter $\zeta$, representing a
dimensionless measure of the liquid momentum at the collapse point (Kelvin
impulse). This parameter is rigorously defined for various jet drivers,
including gravity and nearby boundaries. Combining theoretical considerations
with hundreds of high-speed visualisations of bubbles collapsing near a rigid
surface, near a free surface or in variable gravity, we classify the jets into
three distinct regimes: weak, intermediate and strong. Weak jets
($\zeta<10^{-3}$) hardly pierce the bubble, but remain within it throughout the
collapse and rebound. Intermediate jets ($10^{-3}<\zeta<0.1$) pierce the
opposite bubble wall close to the last collapse phase and clearly emerge during
the rebound. Strong jets ($\zeta>0.1$) pierce the bubble early during the
collapse. The dynamics of the jets is analysed through key observables, such as
the jet impact time, jet speed, bubble displacement, bubble volume at jet
impact and vapour-jet volume. We find that, upon normalising these observables
to dimensionless jet parameters, they all reduce to straightforward functions
of $\zeta$, which we can reproduce numerically using potential flow theory. An
interesting consequence of this result is that a measurement of a single
observable, such as the bubble displacement, suffices to estimate any other
parameter, such as the jet speed. Remarkably, the dimensionless parameters of
intermediate and weak jets only depend on $\zeta$, not on the jet driver. In
the same regime, the jet parameters are found to be well approximated by
power-laws of $\zeta$, which we explain through analytical arguments.
