The left and right sides of the equation Δ S = Q / T

Heat Q and entropy S are two central quantities in thermodynamics. At first glance, Q seems to be the simpler and more intuitive concept, while S is reputed to be difficult. We argue that this impression is misleading: heat Q is, in fact, an insidious quantity. Entropy, on the other hand, has been given its bad reputation unjustly. Once it is recognized that entropy almost perfectly describes what we colloquially mean by ‘heat’, one discovers that it is actually one of the most intuitive physical quantities of all.