  Recent experimental discoveries show that hydrogen-rich compounds can reach
room temperature superconductivity, at least at high pressures. Also that there
exist metallic hydrogen-abundant systems with critical temperatures of few
Kelvin, or even with no trace of superconductivity at all. By analyzing through
first-principles calculations the structural and electronic properties of more
than one hundred compounds predicted to be superconductors in the literature,
we determine that the capacity of creating a bonding network of connected
localized units is the key to enhance the critical temperature in
hydrogen-based superconductors, explaining the large variety of critical
temperatures of superconducting hydrogen-rich materials. We define a magnitude
named as the {\it networking value}, which correlates well with the predicted
critical temperature, much better than any other descriptor analyzed thus far.
This magnitude can be easily calculated for any compound by analyzing
isosurfaces of the electron localization function. By classifying the studied
compounds according to their bonding nature, we observe that the {\it
networking value} correlates with the critical temperature for all bonding
types. Our analysis also highlights that systems with weakened covalent bonds
are the most promising candidates for reaching high critical temperatures. The
discovery of the positive correlation between superconductivity and the bonding
network offers the possibility of screening easily hydrogen-based compounds
and, at the same time, sets clear paths for chemically engineering better
superconductors.
