This document discusses nitrogen fixation, which is the process of converting atmospheric nitrogen gas into ammonia or other nitrogen compounds that can be used by plants and other organisms. It is difficult to fix nitrogen because nitrogen gas is very stable and its triple bonds are hard to break. The document outlines the Haber-Bosch process and Birkeland-Eyde process for industrial nitrogen fixation. Recent research aims to develop more efficient artificial and biological methods of nitrogen fixation, such as through transition metal complexes or engineering nitrogen fixation into food crops.