The holographic sight development started as a search for a sight with improved accuracy, reduced size and greater simplicity. The main component of the sight is a hologram that generates an image of the reticle. This image can appear at any selected distance from the hologram, and can be located either in a plane or in three-dimensional space. The sight accuracy is that of the optics used in forming the hologram, which can be of excellent quality as only one set is needed for hologram recording. The field of view is unrestricted and a 'light-line,' an image of a line in space that extends from the sight to the reticle, guides the observer's eyes to the reticle. Sight designs are reviewed and designs described as the design evolved from a large 20 by 25 cm sight to the current compact sight for small arms. The latest design incorporates a laser diode light source and a pair of holographic elements to make the sight achromatic thus avoiding sighting errors due to laser diode wavelength drift.