Linux

Linux experience is a rite of passage in your journey to become ‘good at computers’. It’s the first step at making your computing experience more involved and less banal. Moreover, many of its tools are required (or strongly recommended) for a huge portion of CTF challenges. For the sake of learning, you should attempt to install a desktop distribution of Linux at some point, but it’s not strictly necessary. Windows Subsystem for Linux lets you use a Linux shell (and the occasional GUI app) from Windows, which should cover 80% of your needs if you’d prefer to use Windows.

It is recommended to start with Ubuntu as your first distro. It’s undoubtedly the most popular (often to the point that it’s used as a stand-in for Linux as a whole) and has the best hardware and software support. You probably don’t need Kali Linux - cool as it may seem, it’s designed for a highly specialized usecase in professional pentesting and many things will often not work as you’d expect them to. You can install any of the tools it provides on another system and have it be more functional overall.