Over the last few releases, the web.config files within new ASP.NET projects have steadily increased in size. For example: the default web.config file that is added to a new web project in Visual Studio 2008 SP1 is now some 126 lines long, and contains everything from tag definitions to definitions of handlers and modules to be included in the ASP.NET HTTP pipeline.

This increase in size is because .NET 3.0 and .NET 3.5 use the same CLR and machine.config configuration file as those shipped with .NET 2.0 – and simply add and update assemblies in the framework when they are installed.  To avoid the risk of us accidentally overwriting customized settings within the original 2.0 machine.config on the machine, we didn’t register the tag definitions, handlers and modules that shipped with the new ASP.NET functionality that came with the .NET 3.0 and .NET 3.5 versions.  Instead, we defaulted to having new projects register these settings within the application’s local web.config file instead.  This was safer – but caused the web.config files to increase and become more complicated and harder to read.