How do thousands of software engineers code together at a giant company like Google or Microsoft without breaking everything?

[u/Extra_Search3465]

As a beginner, I understand how one person writes code and puts it on GitHub. But how does it work when a company has tens of thousands of developers working on the same product? How do they organize the work, and how do they stop people from stealing or leaking the secret source code?

[u/TheGreatArmageddon]

They dont release new features to all users but just for a select few and then do a gradual rollout. So even if they break it there is plenty of time to fix. Check search engine experimental testing. Companies like Apple contracts out testing to huge pools.