In short
In short: GitHub is the place on the internet where programmers keep the code of their software - every file, every change, every version back through time. It's like an archive that keeps every previous version of a document, who touched it and why. It's owned by Microsoft, the tech giant behind Windows and Office. In practice, it's the library where most of the world's code lives.
Behind GitHub stands Git - a system that remembers every change to a piece of code instead of erasing the old one. When a programmer changes a line, Git doesn't delete the previous one - it makes a note of who wrote it, when and why, and keeps both versions. GitHub takes this system and puts it in the cloud, with an interface, comments and buttons, so people in different cities can work on the same code without emailing files back and forth.
Concretely, it looks like this. A team builds an app. One programmer fixes a bug on Thursday evening. He logs the change with one sentence saying why he's doing it. On Friday a colleague sees exactly that change, asks why in a comment underneath it, and if he doesn't like it - reverts to the old version with two clicks. Nothing disappears, everything shows who added what and when.
It exists because before GitHub, teams swapped code in archives over email or on a shared drive - and it was easy to lose track of who had the latest version, who broke what, who fixed what. GitHub solved exactly this problem - and became the place where thousands of people work on the same project at once without stepping on each other.
Everyone uses it - from a lone programmer keeping a personal project, to big companies and entire communities building free software together. Microsoft bought GitHub in 2018 for $7.5 billion and has since built Copilot into it - an AI assistant that suggests code as you type, right in the same interface.
How many people use it and what they do, GitHub sums up every year in the Octoverse report. The edition of October 28, 2026 covers the period from October 1, 2025 to September 30, 2026. By GitHub's figures developers are now over 225 million, and over 40% of pull requests (proposals to change the code) as of September 2026 were started by agents, against 17% in March. The numbers are GitHub's own.
On GitHub nothing gets erased - mistakes stay visible forever, down to the line, the author, the hour. That's why it's also the most honest record that exists of how software actually gets made.
What they don't tell you
For me GitHub is more than a code warehouse. It's the memory of the whole industry. Every time I open someone else's project, I can trace every decision back in time, like reading the team's diary. That disciplines me too - I know every change of mine stays on display.
And that's exactly why I find it hard to accept people who don't keep a history of their work - no versions, no notes on why they did something. GitHub taught a whole generation of programmers that transparency isn't a burden, it's a way to work without fear.
Primary sources
Microsoft News: Microsoft to acquire GitHub for $7.5 billion (official announcement)GitHub: Octoverse 2026 (28.10.2026)The visual is generated code-art, no third-party images.