Debian is one of the original distributions of Linux. Linux is a massive collection of Distributions. It's not just one OS. The big three are Debian, RHEL and Arch. Debian is the base for many Distros such as Ubuntu, Linux Mint, Pop OS, LXLE and so on. RHEL is the base for Fedora and CENTOS as well as SUSE Linux, although the Red Hat team does not work on SUSE Linux. Finally, there is Arch which is the base for Manjaro, Arco, etc. There are smaller bases such as Solos. But the big Three is Debian, RHEL and Arch.
DEBIAN...STABLE IS IT'S MIDDLE NAME
No distribution is as stable as Debian. Things just work. Apps seem to behave, Synaptic is good when problems arise and Debain is your rock solid, well performing system. It's one of the few systems that still has a 32 bit version for older machines and it works very well out of the box. No distribution can compare to the stability of Debian making it a great choice for power users and businesses.
SECURITY AND PRIVACY
Debian is very secure. Security on Linux is far better than on Windows or Mac. Debian, while not the most secure distro, is still miles ahead of Windows and Mac. It usually doesn't have an issue with viruses, especially if a fireall is properly set up. However, problems have happened, so it's not impervious. Make sure you use common sense and make sure your browser's security settings are set to the highest possible that does not impede your browsing experience. Privacy wise, any Linux Distro is going to take care of your privacy. It's the main reason people leave Windows. Mac is very good at protecting privacy, Linux is even better. Debian is no exception.
HARDWARE COMPATIBILITY
If you have a high powered machine that has the newest motherboard, release day graphics card and the newest internals you can buy, Debian is not for you. You would be better served by Fedora or Arch. However if your PC is 2 or more years old, and the stuff inside is the same age, Debain is for you. Debian has great hardware support and it's useable for a vast majority of computers. Even if you are running a pure intel system, Debain is best. Sometimes, some hardware is just not compatible with Linux. That's okay. Not everything will work. Most times, you can get things working if you tinker long enough. However, Debian rarely has this problem. Ubuntu has this issue sometimes because they drop hardware support in favor of new stuff.
GAMING ON DEBIAN
Steam works great on Debian. In fact, Steam OS is based on Debian so it's no suprise that the mother distribution does gaming really well. I think of all the Linux distros I've used, Debian did gaming the best. Ubuntu also does gaming well, but I don't recommend Ubuntu anymore. It's just so broken and there are so many better choices. There is no reason to use it. Steam works great on Debian and Lutris also does great on Lutris. Plus, with wine and steam's proton, windows compatibiltiy has almost been a thing of the past. There are still some things that don't work but that last is getting shorter by the day.
HOW DO I GET DEBIAN
So, if you want to get Debian, the vanilla Debian, you can download it from debian.org however, I find the original Debian hard to install. Using it is fine, but getting it to install is...a chore. So, i recommend using a flavor of Debian that gives you that Debian experience, with easier installer and better system compatibility. To me, that means LMDE or Linux Mint Debian Edition. I believe this distro is the best Debian flavor. In fact, I replaced the main Linux Mint with LMDE. You can get LMDE at linuxmint.com and you will be pleasantly surprised.