Streams (FileStream, MemoryStream)

A stream is C#'s general-purpose abstraction for a sequence of bytes you can read from, write to, or both. The same model works for files on disk, blocks of memory, network sockets, and pipes between processes, which is why so much of the .NET I/O surface is built on the Stream base class. This lesson covers the abstract Stream API itself, the two concrete types you'll meet first (FileStream and MemoryStream), how the OS file handle relates to the managed stream object, the buffering and disposal rules that decide whether your data actually reaches disk, and when to reach for async I/O versus plain synchronous calls.