To generate an XML documentation file from documentation comments in the code, use the /doc option with the csc.exe C# compiler.
In Visual Studio 2013/2015, In Project -> Properties -> Build -> Output, check the XML documentation file checkbox:
When you build the project, an XML file will be produced by the compiler with a name corresponding to the project name (e.g. XMLDocumentation.dll -> XMLDocumentation.xml).
When you use the assembly in another project, make sure that the XML file is in the same directory as the DLL being referenced.
Produces this xml on build:
Interface and class documentation comments
Method documentation comment with param and returns elements
IntelliSense shows you the description for each parameter:
Tip: If Intellisense doesn't display in Visual Studio, delete the first bracket or comma and then type it again.
Referencing another class in documentation
The <see> tag can be used to link to another class. It contains the cref member which should contain the name of the class that is to be referenced. Visual Studio will provide Intellsense when writing this tag and such references will be processed when renaming the referenced class, too.
In Visual Studio Intellisense popups such references will also be displayed colored in the text.
To reference a generic class, use something similar to the following:
Simple method annotation
Documentation comments are placed directly above the method or class they describe. They begin with three forward slashes ///, and allow meta information to be stored via XML.
Information inside the tags can be used by Visual Studio and other tools to provide services such as IntelliSense: