When developing smaller applications that do not have a 
database (or other formal storage mechanism) or data that 
doesn't need to be stored in a database (such as the state 
of a web application), you often still would like to save 
the data for later retrieval. There are many ways to do 
this, but many of them are subject to a lot of extra code 
(work) and extra time spent debugging. With .NET, there is 
now an easy way to add this functionality to your code with 
only a few lines of easily tested code. This easy way is 
called serialization.

Serialization is the process of converting an object into a 
stream of bytes. On the other hand Deserialization is the 
process of creating an object from a stream of bytes. 
Serialization/Deserialization is used to transport or to 
persist objects. Serialization can be defined as the 
process of storing the state of an object to a storage 
medium. During this process, the public and private fields 
of the object and the name of the class, including the 
assembly are converted to a stream of bytes. Which is then 
written to a data stream. Upon the object's subsequent 
deserialized, an exact clone of the original object is 
created.