Note: [Deprecated Content] This was written while ASP.NET and .NET Core was in beta (around beta5 or beta6). Since then a lot of stuffs have changed and moved around. Stuffs described below may or may not be true for current stable releases of ASP.NET Core - Configuration feature. I recommend not to follow along and get confused. Use official configuration documentation that explains it correctly - With the upcoming release of .NET 4.6 and ASP.NET 5 (currently in BETA phase) one namespace that is getting new look (re-written) is System.Configuration. If you have not already read then I recommend you to take a look at getting started post by Louis DeJardin - ASP.NET vNext Moving Parts: IConfiguration He has also explained other moving parts which are some interesting reads. Why you ask? Louis explains few reason why System.Configuration needs to » Read more