I know this must be answered somewhere, but I'm going to ask it anyways as the suggested duplicates are not the right ones. I'm not looking for "well this is a solution" or "well I like this software" I want to know the solution the big websites use.How do large websites like Google or Facebook work collaboratively on all their websites and branches of their company? Do they use GitHub or something?I have worked collaboratively with other developers before and the most annoying this is overwriting each other in the FTP. I had to chat with them each time I wanted to change a file like "opening this file" and "closed this file."How does Google manage thousands of employees accessing files?