In fact, MSDN is a development virtual community with Visual Studio and Windows as its core, including technical documents, online electronic tutorials, online virtual laboratories, Microsoft product downloads (official and beta versions of almost all operating systems, server programs, applications and development programs, as well as various driver development packages and software development packages), blogs, BBS, MSDN webcasts, MSDN magazines cooperating with CMP and a series of other services.
Most of the information about MSDN that users come into contact with may come from the MSDN library. The MSDN library is generally regarded as MSDN, which contains the technical development documents and scientific documents (including some source codes) of Microsoft's fully developed product line, as well as excerpts from back issues of MSDN magazine and excerpts from some classic books. The link for online browsing is/en-us/library/ms123401.aspx.
Speaking of help documents, different versions of VS will be equipped with different versions of MSDN libraries of different sizes. You can install different versions of the MSDN library according to your own development needs, or you can read the query help document directly online without installing it.