Since Pauling formalized the idea in 1932, electronegativity has grown into a useful tool for rationalizing trends in charge transfer, bond polarity, bond strength, reactivity, and various chemical properties. Electronegativity is a simple and intuitive concept; in that it quantifies the ability of atoms (or groups of atoms) to attract (or hold on to) electrons. Over time, many different electronegativity scales have been proposed, each attempting to tie this chemical concept to different physical properties, typically including ionization energies, electron affinities and other spectroscopical properties of valence electrons. Some electronegativity scales are based on physical properties of bonded atoms, such as the Pauling or Walsh scales, while other are defined from properties of isolated atoms, such as the Mulliken, Allred & Rochow and Allen scales. A particular challenge with electronegativity is to reconcile its many definitions with its common practice and resulting chemical predictions (and failed predictions). How electronegativity changes upon bond formation is, consequently, a long debated topic. A well-known postulate by Sanderson states that electronegativity of atoms in molecules should equal the mean of the values for the isolated atoms. In other words, the electronegativity of isolated atoms are postulated to equalizes when bonded together inside molecules or materials. Sanderson's idea was supported by Parr and coworkers, who defined electronegativity as the negative of the chemical potential, in turn a homogeneous value across any system in equilibrium. Chemical potentials determine where electrons flow. Nevertheless, alternative viewpoints on electronegativity equalization have been voiced by several. One of the critiques to Sanderson's postulate is rooted in the chemical expectation that electronegativity should reflect how the nature of atoms differs, even when they are bonded in a material. Equalization requires all atoms to adopt the same electronegativity within a molecule, regardless of the element. A related objection is that Sanderson's postulate requires electronegativity to be defined as the chemical potential. In other words, Sanderson's postulate excludes a host of electronegativity definitions, many of which are by their own right useful. Many opposing viewpoints on electronegativity have merit but it is outside our scope to weigh them. We stress that this work is not intended as a critique of related theories and methods that can provide chemical insight (e.g., Refs. 50-62). Rather, we aim to develop a complementary perspective.