Modern cognitive radio technology allows unlicensed users, also known as cognitive radio CR or secondary users, to utilize idle licensed spectrum. It was discovered that the spectrum incompetence and inefficiency issues could be resolved using the CR technology. The significant underutilization of spectrum at the moment is the primary impetus behind CR technology. Surprisingly, primary user PU had full permission to use his spectrum band, so CR must refrain from interfering with it. In this section, we will talk about energy detection, which is one of the spectrum sensing techniques used in CR functions. We will also talk about how to get the best spectrum that is available, how to find a hole in the spectrum, how to figure out the best threshold voltage that will produce the least amount of false alarms, and how to use MATLAB simulation to improve the energy detection sensing algorithm