revisit the point I made about the appSettings not being type-safe. If you have multiple places where you access your appSettings, you might not like having to repeat the (string) key everywhere, and having to convert the string value to the correct type every time. A simple solution to this is to create your own class that wraps the call to ConfigurationManager:
In all other locations of your code, you can now call this class and be sure you’re getting an integer.
This article aimed at showing you the basics of the app.config file, and some best practices. The app.config file is a basic piece of the .NET Framework, yet I’ve seen several projects putting their configuration in other places (like plain text files or the registry). Unless you have a very good reason to do so, it’s more convenient and familiar to use the app.config file. You can change it easily, the .NET Framework supports it out of the box and almost all .NET developers know how it works.