The reheating stage remains a strongly model-dependent and theoretically poorly understood part of the inflationary paradigm. However, the possibility that it could one day be tested via its gravitational wave signatures, and that it may also be related to other relicts such as dark matter or baryon asymmetry, continues to motivate studies with many models and methods. I review the general framework as well as some recent developments from this field, as inspired by this week's TH workshop on particle production in the early universe.