<p>The <b>Aerospace and Defense</b> category comprises industries and establishments primarily engaged in one or more of the following:</p> <ul> <li>Development, manufacture, and distribution of civil and military aircraft, missiles, space vehicles, military equipment, and the auxiliary equipment, parts and supplies.</li> <li>Development, manufacture, and distribution of aerospace engines, propulsion units, and auxiliary equipment or parts.</li> <li> Development and production of aerospace and military product prototypes. </li> <li> Aircraft conversion (i.e., major modifications to systems). </li> <li> Complete aircraft or propulsion systems overhaul and rebuilding (i.e., periodic restoration of aircraft to original design specifications).</li> <li>Services that specifically support these industries (e.g., consulting, marketing, associations, etc.).<br> </li> </ul> <p>In general, the aerospace industry is engaged in the research, development, and manufacture of flight vehicles, ranging from unpowered gliders, sailplanes and lighter-than-air craft up though space vehicles. The term aerospace is derived from the words aeronautics and spaceflight.</p>