Explanation
[ is an alias for the program test, so you can call man test for more info.
&& is bash syntax for conjunction. In A && B, B will only be called if A returned a exit code >0 (error). You can call man bash for more info.
|| is bash syntax for disjunction. In A || B, B will only be called if A returned exit code =0 (success).
true and false are programs that just return exit codes 0 respectively 1.
If you talk about version control: https://alternativeto.net/software/git/
Git != GitHub though.