How many different versions of 'CSI' are there?

There are several different versions of the "CSI" franchise, including the original series "CSI: Crime Scene Investigation," which aired from 2000 to 2015, and its spin-offs "CSI: Miami," "CSI: NY," and "CSI: Cyber." Additionally, a revival series titled "CSI: Vegas" premiered in 2021. Overall, the franchise consists of four main series and a revival, making for a total of five distinct iterations.