How to make edits on a working site and not mess it up?

Question

Programming

On one of the sites that I am familiar with, which is being developed from scratch, they make 3 subdomains (dev1, dev2, dev3) for 3 programmers. First, the necessary edits are made on the subdomain, tested, and then rolled out to the working site.
How to organize it correctly for a WordPress site? Which methods, services, tools, etc. to use.
I use such things as backup, child theme, etc., but this does not prevent errors, but only makes it possible to roll them back, which takes time and, possibly, the site is not working.
PS How to practically organize work with git?
1. Created a project folder in the computer. There are only theme files in the folder.
2. Created a repository, linked to github.
What's next? Do I make all the edits first on the computer in the files, then I make a commit and then only transfer them to the hosting? If it turns out some kind of jamb, then I roll back?

Answer 1

And if there are not 3, but 300 - will you open 300 subdomains? Everything is made easier. SourceControl (Git , Mercurial , TFS) - it contains the main Release branch, from which you can branch each coder with his own direction of work. According to the data - ideally 3 database servers are made - Dev, Test, Release - it's more difficult here. Database version control exists 100% only for the database schema, and then at the level of SQL scripts. There will be problems with the data. You can deploy and test on the encoder's local machine. It is not necessary to allocate resources on web servers for them. Well, something like this. Although if you have a very unique project architecture that does not allow you to use the solutions mentioned - then I apologize for the wasted time.

Answer 2

Have you really heard of version control systems?