Git Ignore Scenarios

Broadly, there are three scenarios where one might want to ignore files.
Specific to personal workflow
modify 
.git/info/exclude
Specific to project secrets
Scenarios like .env files for running a project locally. Here you can modifiy the repo level
.gitignore
Always ignore
If certain files should be ignored regardless of sitatuion, this can be configured globally.
Unless otherwise configured in the 
~/.gitconfig, the ignore file will be found at 
$XDG_CONFIG_HOME/git/ignore. if that value is not set or empty, check
$HOME/.config/git/ignore.
References
https://git-scm.com/docs/gitignore