What was the first OS you ever used?

Before clean installs, dual-boot menus, and cloud everything, there was that first encounter, the moment you realized a computer wasn't just hardware, it was a system with a personality.

Maybe it was a beige family PC running something like MS-DOS, where every command felt like a small act of discovery. Or perhaps it was the friendlier chaos of early Windows versions, including that of Windows 95 with its Start menu and that unmistakable startup chime. Some of you might go further back, to Classic Mac OS, where clicking icons felt almost magical.

First operating systems tend to stick. They shape how you think about files, folders, multitasking, even what "fast" feels like. For some, it was a locked-down school computer running a stripped-back Linux distro. For others, it was tinkering at home, reinstalling Windows XP one too many times, or discovering open source through early versions of Ubuntu.

There's also a generational shift worth noting. A growing number of users didn't start with a traditional desktop OS at all, but with mobile platforms like Android or iOS, where the concept of a "file system" is almost invisible. That changes the baseline for what computing even means.

So here's the question: what was the first OS you ever used, and what do you remember about it? Was it intuitive, frustrating, or something you had to fight to understand?

And looking back, did it shape the way you use computers today?