If you are.Net developer, then you will be obviously aware of DLLs. DLL stands for Dynamic Link Library. This file format used for holding multiple codes and procedures for Windows programs. If you are the C# developer then entire namespace will be store into DLL file. You can not read code written in DLL files, But usually, developers need it.
ILSpy is a Software that allows us to read C#/VB from that DLL. It was an open source project. You can download ILSpy from SourceFroge.
After downloading it you need to click on open from the toolbar and select all file that you want to extract.
After selecting DLL file you can expand all to see its members. For example, here I have selected MongoDB Driver’s DLL. It contains
DefaultAuthenticator class under