And within the web.config an example below:
<configuration> ... <system.web> <compilation debug="true" ... > ... </compilation> </system.web> </configuration>
Note: Be sure to disable ASP.NET Debugging when done with your Debugging of your application - leaving it on could cause numerous issues for exampe:
1) The compilation of ASP.NET pages takes longer (since some batch optimizations are disabled)
2) Code can execute slower (since some additional debug paths are enabled)
3) Much more memory is used within the application at runtime
4) Scripts and images downloaded from the WebResources.axd handler are not cached