.NET: How .config files works?

For 开发者_StackOverflow中文版me it a little bit hard and frustrating to understand how app.config, web.config files work on deep level.

Is it any document which can describe format, internal implementation and parsing of .config file.

This is at least a good start: http://msdn.microsoft.com/en-us/library/system.configuration.configurationmanager.aspx. You can follow the links from there to get more information as well.

One thing worth mentioning that people commonly get hung up on - configuration files are for applications, not libraries. It doesn't make a lot of sense to give a library its own configuration file, since the standard, accepted ways of accessing configuration (ConfigurationManager) operate based on the executing process.

Config files are well documented. I would start on MSDN here: Configuration Files. This gives an overview of how the config files work, and has reference links to how to accomplish various development tasks.

There's full documentation for each schema for app.config, web.config, machine.config, etc. here: Configuration File Schema for the .Net Framework