Abstract :
Observing high energy sources implies inventing new ways to observe the universe. Traditional techniques like the ones used in optical, infrared or ultraviolet bands are useless for energy of x-rays and higher. We will review, on the one hand, the techniques needed to focus high energy photons and bring them to our detectors. On the other hand, we will review what kind of detectors we need. All that will be put into context on what kind of focusing technique and detector better suits each energy range. Furthermore, examples of current, past and future instrumentation will be given.
