What is App.config in C#.NET? How to use it?

Question

I have done a project in C#.NET where my database file is an Excel workbook. Since the location of the connection string is hard coded in my coding, there is no problem for

Answer 1

Just adding one more point

Using app.config some how you can control application access, you want apply particular change to entire application use app config file and you can access the settings like below ConfigurationSettings.AppSettings["Key"]