Things scale in size. Things scale by a scale factor. Relationships scale in particular ways: volume scales differently than area, which scales differently than length. Scaling sometimes seems to occur with a fractional exponent. Scaling is observed in biology, in physical systems, in economics, in networks, and in cosmology. Does the common appearance of scaling in so many different phenomena indicate that scaling is deeply connected to entropy or some other fundamental aspect of the distribution of energy? Why is scaling ubiquitous, and what does its ubiquity tell us, if anything, about underlying principles, if there are any?