I'll bet you a dollar that, as a programmer (or just a regular person), you've seen a .md file before. Don't believe me? Think I just lost the bet? Sorry to break it to you, but I've already won — even if you have no idea what a .md file is — because you're reading one right now.
Why we just tell the AI to write the README and move on
Lately I've noticed that, as programmers, we tell AI "hey, write the README for my app, thanks in advance," and that's not wrong in itself — I'm not saying you have to write it yourself in whatever format you like. But do you actually know what it says? Did you read it before pushing it to your GitHub repo? That's what I want to talk about today.
What is a .md file, really?
It's simple: a .md file is a lightweight markup file type used to format text (headings, bold, italics, lists, and so on). They're widely used because their structure is easy to understand, and they're what GitHub — the largest code repository in the world — uses to display documentation. If you want to dig into the structure itself, you can check out this intro to Markdown.
Because they're so simple to create and read, AI models understand exactly what they're reading and writing. And that's precisely why these files matter so much.
The poorly explained favor
Imagine asking a family member for a favor. If you dump everything on them at once, they probably won't understand what you're actually asking. For example: "hey, there's a notebook in my drawer I forgot to bring to college, can you bring it to me?" They'll be willing to help, but which drawer? Which notebook? How much time do they have?
It's better to leave detailed instructions: "in my room, right as you walk in, there's a nightstand on the right side of the bed, not the left. In the third drawer from the top, there's a lime-green notebook. Can you bring it urgently, please? I need to turn it in by 11 am." That's far more detailed, gives your family member proper context, and leaves no room for mistakes.
Markdown files — at both the code and documentation level — work exactly the same way. In programming and on the web, they're used to write documentation, blog posts (like this one), and a lot more. But do you know what else they're good for? For our best tech friend: AI.
Why this applies to AI too
In programming projects, the number of files is massive. You can have thousands, even millions, of files scattered around and connected to each other through modularization, to the point where you can get lost yourself among all that code. Something similar happens to AI: it doesn't exactly get lost, because it'll try to give you a solution even if it has to circle around until it fulfills what you asked — but that burns through the usage you could spend asking for something else.
Now picture AI as that same family member. If you tell it something like "hey, I've got a bug somewhere in the code, good luck finding it," it'll probably wander around checking file after file, burning tokens and spending energy on something you could have solved much faster with the right context. And that's not all: how is it supposed to know what your code is about if nobody explains it? That's exactly what markdown files are for.
The files worth knowing
Let's talk about a few important ones:
README.md: probably the most famous of the group. It's not just so someone landing on your GitHub says "wow, nice repo" (nobody actually notices that). It's there so people can figure out how the code works without reading through all of it: install instructions, a short context of the app, commands, and other relevant info — for developers and for AI alike. You can check out a real example on GitHub.CONTEXT.md: this one has gained a lot of traction since AI arrived. It gives AI context on how you want it to work, write code, and what your app is about. AI is designed to check this document before doing anything, to understand your application's context. You write it once, and AI reads it every time. Here you can detail your architecture, your tech stack, the "heart" of the project, coding standards, and more. It's a living file — you update it every time you add new functionality. You can check out a real CONTEXT.md template.AGENTS.md/CLAUDE.md: similar to CONTEXT, but this one is for giving your AI behavior rules and invariants — which commands to run for your project to work, which conventions to follow. For example, I always add that it should leave code documented in first person and in detail; that way, when I review what it implemented, it's much easier to understand what it was trying to do. Worth noting: AGENTS.md is no longer just an informal convention among developers — it's now an open standard adopted by GitHub Copilot, Cursor, OpenAI Codex, and Google Jules, among others. You can check out the official AGENTS.md standard, a real production example, or this curated collection of CLAUDE.md files.ARCHITECTURE.md: an old-school one. Extremely important when working with other people, or even just so you don't forget your own software's architecture. Here you write how your application actually works: where data is stored, how your backend and frontend are structured, the design philosophy you want to follow. AI can read it and understand why it should respect that design and why files go where they go. You can check out a real ARCHITECTURE.md example.DOCS/CHANGELOG.md: these hold documentation (like how an API works) and a record of changes to the application. That way, both AI and developers understand why a decision was made and when. Check out Keep a Changelog, the most widely used standard for this type of file.
And there are plenty more like these. This isn't about now having to follow a rigid checklist to build sustainable software. It's simply a rope you leave for someone else — even for your future self — so that when they fall into that "feeling lost" pit, they can climb out more easily.
This isn't carved in stone
I hope you now understand why these files matter, and that you take the time to read the .md files of a project you're contributing to, or your own. Don't let README templates stay exactly the same forever. Instead of asking AI to do the same thing over and over, write a solid ARCHITECTURE.md, AGENTS.md, and README.md once. Or just ask AI to help you draft them, read them, request changes, and then create the final files that will help you maintain your code more easily. Nothing here is set in stone, so don't be afraid to change them either.
Writing documentation is far easier than it was a few years ago. Thankfully, AI can gather information from what you've written and properly document everything in your code — making things easier for you, for other devs, and for AI itself.
AI is a tool that helps us get the most out of our work, and it's not going anywhere anytime soon. AI is here to stay. And that's exactly what we'll talk about in our next article.
Have a great week, and don't stress about the pace of your progress.