How to create Application Configuration files in .NET apps

I was getting mad while debugging my app - I could not find where a specific app.config appSetting key's value was coming from. I checked the machine config file to no avail.

I then simply followed exactly MSDN instructions regarding app.config file creation, and now the app setting key value is correct. Seems this is the way correct way to ensure you know exactly what your deployed config file will look like.

Don't forget to set the file's Build Action (Properties window) to Content. If you leave it as None, it will not be deployed.