Around 30 years ago, much of the research into platinum coordination chemistry was being driven either by research into one-dimensional, electrically conducting molecular materials exploiting the stacking interactions of planar complexes, or by the unprecedented success of cis-Pt(NH3)2Cl2 (cisplatin) as an anticancer agent. At that time, a number of simple platinum(II) compounds were known to be photoluminescent at low temperature or in the solid state, but almost none in fluid solution at room temperature. Since that time, several families of complexes have been discovered that are brightly luminescent, and a number of investigations have shed light on the factors that govern the luminescence efficiencies of Pt(II) complexes. Over the past decade, such studies have been spurred on by the potential application of triplet-emitting metal complexes as phosphors in organic light-emitting devices (OLEDs), where their ability to trap otherwise wasted triplet states can lead to large gains in efficiency. In this contribution, we take a chemist's perspective of the field, overviewing in the first instance the factors that need to be taken into account in the rational design of highly luminescent platinum(II) complexes, and the background to their use in OLEDs. We then consider in more detail the properties of some individual classes, highlighting work from the past 3 years, and including selected examples of their utility in OLEDs and other applications.