Definition
GitHub is a web service that stores code, the blueprints of computer programs, on the internet and lets many people work on it together. It safely keeps every edit ever made to the code, and you can share it with developers around the world at any time.
Where your computer's time machine goes online
Everyone has saved a document under names like "final.docx," "final_v2.docx," and "final_REALLY_final.docx." In the programming world, people use a specialist tool called Git to record every single edit, like a time machine.
But Git mostly keeps its records inside your own computer. If your computer breaks or gets lost, all that hard-earned history can vanish in a moment. GitHub is the safe place in the internet cloud where you back up your Git time machine's records from your computer.
Once your code is on GitHub, you can pick up your work at home, in a cafe, or at the office, anywhere with an internet connection. It's the starting point for stepping out of your own computer and connecting with developers worldwide.
The magic of working together without bumping heads
When several people edit one document at the same time, it's easy to accidentally erase what someone else wrote. On GitHub, you use a Git feature called a "branch." It lets you leave the original code untouched and work safely on your own offshoot.
To be a bit more precise: when you want to bring your finished new feature into the original, you submit a formal proposal called a "pull request." Usually, teammates review the code you wrote and approve it, and then it gets merged into the one original program.
Thanks to this system, hundreds of developers can build one huge program at the same time without their code getting so tangled. If their changes clash, the clash can be found and sorted out before merging. And if something goes wrong after a merge, you can always roll back to an earlier, working version.
The social network for developers and the home of open source
GitHub is more than a place to store code. It's a huge town square where developers from around the world gather. Like social media, you can follow other people's work and give a "star" to projects you like.
It's especially the heart of open-source culture, where anyone can freely look at code and help improve it. World-class technologies, like the Python programming language and many AI programs, grow on GitHub through the hands of countless developers around the globe.
Developers use the record of work piling up on GitHub as a résumé and a portfolio of their skills. Every day you write code, a little green square fills in on a calendar, like a lawn being planted. Some people see it as a sign of a developer's steady habits.
Common misconceptions
Git and GitHub have similar names, so they are the same program.
Git is a software tool that tracks changes to your code on your own computer. GitHub is a web service that puts those records in the internet cloud so you can share them with other people.
Where you meet it
Developers from around the world gather on GitHub to build and improve open-source projects like Python and AI programs together.
When applying for jobs, a developer submits their GitHub address as a portfolio showing the code they wrote and their teamwork experience.
In one sentence
GitHub is a platform that safely stores your code's edit history on the internet and helps you collaborate in an organized way with people around the world.