This is the Introduction to a special section of the Review of International Political Economy, 26 (1), 2019, 1-24, co-authored with Caroline Kuzemko and Andrew Lawrence. It has a DOI of 10.1080/09692290.2018.1553796 (https://doi.org/10.1080/09692290.2018.1553796). The aim of the special section is to show how energy markets are changing: in essence, in scale, in constitution, in spatial characteristics and in distributional implications. Energy markets are today bigger than ever before, in that they now encompass an ever wider range of actors and sites of interaction. They are also almost certainly more complex institutional entities than at any previous time in their history. When politicians express faith in 'the market' to cater for all of their energy needs, then, they are now typically doing so whilst the exchange relations conducted between energy buyers and energy sellers look to be modelled less and less on the pure abstraction of 'the market'.