.gitignore file specifies intentionally untracked files that Git should ignore.

THE PROBLEM: Whenever I start a new project, I always forget to add some files or folders...!

The gitignore github project comes to the rescue with its collection of ready-made templates that simplify the creation of the .gitignore file by adding some common files and folders to be ignored.

It is also very convenient when approaching a totally new programming language.

There is also another cool project, if you are more to create .gitignore files on the fly with a simple UI: https://gitignore.io