  On the basis of dynamical principles we derive the Logistic Equation (LE),
widely employed (among multiple applications) in the simulation of population
growth, and demonstrate that scale-invariance and a mean-value constraint are
sufficient and necessary conditions for obtaining it. We also generalize the LE
to multi-component systems and show that the above dynamical mechanisms
underlie large number of scale-free processes. Examples are presented regarding
city-populations, diffusion in complex networks, and popularity of
technological products, all of them obeying the multi-component logistic
equation in an either stochastic or deterministic way. So as to assess the
predictability-power of our present formalism, we advance a prediction,
regarding the next 60 months, for the number of users of the three main web
browsers (Explorer, Firefox and Chrome) popularly referred as "Browser Wars".
