Using this feature to integrate the .Net namespaces (assemblies) , dll (dynamic link library) , interoperable components, tlb (type library file) and projects. This help us to use the necessary functionality to our projects.
Either right click on the project in the solution explorer or select the project menu (Website menu in web developer edition) to select the add references.
Select either .Net or COM or BROWSE or PROJECT tab to choose required object to use the reference into your project.
Add web references:
Using this feature to integrate the web service with ASP.Net pages. Type the URL for the web service (asmx?wsdl) than add the reference with web site. Valid web service will create the ‘Discomap’ (web service discovery) file, ‘wsdl’ file and related ‘xsd’ files.