.NET: web.config and machine.config

As we know that: The Configuration system first searches settings in (machine.config) file & then looks in application configuration  files (web.config)
So, the difference between both of them is: “Web.config” files apply settings to each web application, while “Machine.config” file apply settings to all ASP.NET applications.

Setting stored in Machine.config file are:
1. Connection strings
2. Membership
3. RoleManager
4. Profile
5. HttpHandlers

Setting stored in web.config file are:
1. Database connections
2. Session States
3. Error Handling
4. Security
Next Recommended Reading Stop ASP.NET web.config inheritance