X-ray telescopes are simply collectors that focus x-ray electromagnetic radiation to a point which is usually occupied by some type of a detector. Their design vaguely looks like that of an optical telescope except that, since x-rays are absorbed by direct reflection, they have to be focussed by a slightly different technique that resembles stones skipping off of water, and being collected at a single spot for 'counting'. These telescopes let astronomers look at very high energy phenomena occurring on the surface of the Sun, or in distant galaxies and stars.