Okay, let’s talk about this `ttx` thing.

I kept bumping into files with a `.ttx` extension a while back. Honestly, for the longest time, I wasn’t entirely sure what they were. You see these file types pop up, right? And sometimes it’s obvious, like `.txt` or `.jpg`. But `.ttx`? That one had me scratching my head a bit.
Figuring it Out
So, my first instinct was just trying to open it. Double-click, hope for the best. Didn’t work. Tried opening it with a plain text editor. That actually showed something – looked like a bunch of code, specifically XML. Lots of tags and stuff. But it didn’t immediately tell me what the purpose was.
I asked around a little, did some digging. You know how it is, you poke at a problem long enough, you eventually find someone or something that points you in the right direction. It wasn’t super straightforward because searching for short terms like “ttx” can sometimes give you a lot of unrelated junk.
So, What Is It?
Turns out, in the contexts I was seeing it, `ttx` usually stands for a specific thing related to fonts. Yeah, like the fonts you use on your computer or website. There’s a toolset, I think it’s called `fonttools`, that programmers and font designers use.
This tool can take a regular font file, like a TrueType (`.ttf`) or OpenType (`.otf`) font, and basically unpack it into an XML format. That XML file is what gets saved as a `.ttx` file. It’s just a text-based description of the font – all the shapes, the spacing, the rules, everything.

Why bother? Well, a few reasons I figured out:
- It makes the font data human-readable. You can actually open the `.ttx` file in a text editor and see the structure.
- You can edit it! If you know what you’re doing, you could tweak the font data directly in the XML file.
- Then, you can use the same `fonttools` thing to pack that `.ttx` file back into a working `.ttf` or `.otf` font file.
- It’s also apparently useful for comparing different versions of a font, because text files are easy for version control systems (like Git) to handle.
So, that’s the gist of it from my experience. When I see `.ttx` now, especially floating around font files or design assets, I know it’s likely that XML representation of a font, probably made with `fonttools`. It’s just a way to get under the hood of a font file using plain text. Pretty handy once you know what it is.