Why scientists care
Electronegativity is a model for an atom’s tendency to attract electron density when it is bonded.
Differences in electronegativity help us reason about bond polarity, but they do not turn bonding into a rigid binary classification.
A concrete example
A polar H–F bond reflects fluorine's much stronger attraction for bonding electrons.
Try to notice
Science becomes memorable when a definition is connected to something measurable or observable.