Abstract The chemical etching of charged particle tracks swiftly destroys almost all of that radiation damage physics which is stored, as energy, and which is the characteristic ‘signature’ of a latent track. The etched track is a binary counter — track present/track not — and is the basis of those numerous applications so well known to us — in geochronology, geothermometry, paleobotany, paleontology, environmental monitoring, plate tectonics, hydrocarbon exploration, and so on. A case is made for a fundamental re-examination and assessment of the latent track, not only in glasses, and amorphous solids, but especially in crystals, — metals, insulators and semiconductors. For crystals it is emphasized that each track is unique. In a given direction vector the energy will never by the same, nuclear Sn and electronic Se stopping contributions will differ, and the statistical nature of close encounters will make conversion of the trajectory, which is dynamic, to the track, which is its static legacy, quite specific to the case. The passage of fission fragments through solids is discussed in terms of the physical processes taking place. The critical part played by the so-called deltas rays and the equations describing their track-forming properties are outlined. It is shown that a complete and satisfactory description of the “fission spike” is not yet available but that by concentrating on those crystals which display clear latent tracks in the transmission electron microscope it will shortly be possible to produce a first generation predictive model. Anisotropy of the lattice and variations in the atomic bonding are two of those crystalline features which hold the key precisely to understanding the track registration at the atomic level. Macroscopic chemical etching and “development” of latent tracks then depend on variations with time and angle of the track etch velocity vt, which in turn is a function of the microscopic spatial distribution of defects. Electron microscope images of fission tracks in a variety of solids are described and contrast calculations discussed in general. Oscillatory TEM contrast along a track can be both real and imaginary. This creates the need for extreme care in interpretation. Other features of TEM images of fission fragment tracks are considered. A plan for future research is outlined.