Data Contract vs Message Contract in WCF

namespace CustomerService
{
// NOTE: You can use the "Rename" command on the "Refactor" menu to change the interface name "ICustomerService" in both code and config file together.
[ServiceContract]
public interface ICustomerService
{
[OperationContract]
Customer GetCustomerDetails(int CustId);
}
[DataContract]
public class Customer
{
private string t_Name;
private int t_Age;
private int t_Salary;
private string t_Designation;
[DataMember]
public string Name
{
get { return t_Name; }
set { t_Name = value; }
}

[MessageContract(IsWrapped = true, WrapperName = "GetEnterpriseInternetInfoRequest",
WrapperNamespace= "http://techkatak.com/EnterpriseService")]
public class GetEnterpriseInternetInfoRequest
{
[MessageHeader(Namespace = "http://techkatak.com/EnterpriseService")]
public string LicenseKey { get; set; }
}
[MessageContract(IsWrapped = true, WrapperName = "GetEnterpriseInternetInfoResponse",
WrapperNamespace = "http://techkatak.com/EnterpriseService")]
public class GetEnterpriseInternetInfoResponse
{<br />
}