In 1958, a Chinese airplane took its very first flight, and it went on to have a pretty long career in the military. This airplane, called the H-6 bomber, also worked for the Egyptian and Iraqi Air Forces, but it retired from those jobs in 1991 and 2000, respectively. After that, there were many different versions of this plane made.
With some changes in how it worked, how much stuff it could carry, and how it could refuel. So, over the years, this airplane got updated and improved in various ways. It’s performance enhanced with each upgrade. It’s kind of like how you might upgrade your computer or phone to make it better and more modern.