The simplest level of file access just involves retrieving information about existing files and directories and performing typical file system operations such as copying files and creating directories.
.NET provides five basic classes for retrieving this sort of information. They are all located in the System.IO namespace (and, incidentally, can be used in desktop applications in exactly the same way they are used in web applications). They include the following:
The Directory and File classes, which provide static methods that allow you to retrieve information about any files and directories visible from your server
The DirectoryInfo and FileInfo classes, which use similar instance methods and properties to retrieve ...