Live cell imaging in particular, like many other imaging tasks, depends on making good use of the available fluorescence light. The detector is a critical component in the light path with regard to photon efficiency. This tutorial explains the underlying hybrid detection technology (exemplified by Leica HyD) and compares it to photomultiplier technology. The implications of hybrid detection design for imaging and photon counting are discussed. The tutorial closes with a brief summary of photon counting in the context of imaging.