A stream is a set of data flowing from a source or a sink.
A stream may concerne not also files but equally data transfer on the network or in memory.

Under .NET, the Input/Output operations are essentially managed by the abstract class Stream.

Being an abstract class, it's impossible to instanciate it directly. It's primary goal is to allow a standardized way of performing I/O operations.

A number of classes deriving from Stream exists, these may be splitted in two categories.

The first category contains all classes implementing the Stream class for a specific I/O operation. These classes are:

• FileStream, to work with files;
• NetworkStream, for networked data transfer;
• MemoryStream, for memory exchange;

The second category contains classes deriving from Stream but enhancing what a Stream has to offer. They may be considered as a layer over the base functionality offerd by the Stream class.
This category contains the following classes:

• BufferedStream, which allow to perform buffered operation over a Stream. Due to the fact that datas are not directly written to the stream, the number of I/O needed to perform the operation decrease, thus increasing the execution of the operation;
• CryptoStream, which allow the data written or read from the stream to be encrypted or decrypted.

The following drawing summarize the stream classes hierarchy:

If you want, you can continue to:

• The Stream class
• Asynchronous I/O
• The FileStream class
• StreamReader and StreamWriter
• BinaryReader and BinaryWriter
• The NetworkStreamclass