What Is Citrulline?

Citrulline is one of the more popular supplements for enhancing endurance and athletic performance. The more I looked into it, the more interested I became. Although I did not want to use performance-enhancing drugs, I was definitely interested in natural ways to make the process easier. I fell down an internet rabbit hole of studies and articles about this amino acid. Like most people, I wanted to understand what I was taking and know for certain that it is a good choice. What is citrulline? Is this supplement safe? Could it help me to achieve my fitness goals?