Internal implementation package not meant for direct consumption. Please do not reference directly. Provides types that allow reading and writing to files and types that provide basic file and directory support. Commonly Used Types: System.IO.FileStream System.IO.FileInfo System.IO.DirectoryInfo System.IO.FileSystemInfo System.IO.File System.IO.Directory System.IO.SearchOption System.IO.FileOptions When using NuGet 3.x this package requires at least version 3.4.