Serializing a class: "Serialize" or "DataContractAttribute"?

Question

What's the difference between using "Serialize" or "DataContractAttribute" while you want to make a class seriallizable?

 

Compiler warns: 

 

Type 'MyNAmeSpace.MyClass' cannot be serialized. Consider marking it with the DataContractAttribute attribute, and marking all of its members you want serialized with the DataMemberAttribute attribute. If the type is a collection, consider marking it with the CollectionDataContractAttribute. See the Microsoft .NET Framework documentation for other supported types.

 

Why doesno't it suggest using [Serialize] attribute?

 

P.S. the class is not used for any web service. It's a normal class which I want to write to DB.