Serialization is
the process of mapping an object to a BSON document that can be saved
in MongoDB, and deserialization is the reverse process of
reconstructing an object from a BSON document. For that reason the
serialization process is also often referred to as "Object
Mapping." 
Serialization is
handled by the BSON Library .
Creating a class
map
To create a class map in your intialization code write:
    BsonClassMap.RegisterClassMap<testClass>();
If you want to control the creation of the class map you can provide
your own initialization code in the form of a lambda expression:
    BsonClassMap.RegisterClassMap<testClass)(cm => {
        cm.MapProperty(c => c.SomeProperty);
        cm.MapProperty(c => c.AnotherProperty);
    });
When automapping a class there are a lot of decisions that need to be
made. For example:
Which fields or properties of the
	class should be serialized 
	
	Which field or property of the
	class is the "Id" 
	
	What element name should be used in the BSON document