Encapsulation

Given a class, the sum of its members complexity should be less than the sum of its parts in isolation.

Suppose there is a Customer entity like this:

public class Customer
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public string SSN { get; set; }
    public bool Active { get; set; }
    public string ActivatedBy { get; set; }
}

The complexity of the previous class is the same if there were variables like the following:

    Guid Id;
    string Name;
    string SSN;
    bool Active;
    string ActivatedBy;

Classes that are similar to a bag of data leaks unnecessary complexity. Consider reducing the complexity with something like:

public class Customer
{
    public Guid Id { get; protected set; }
    public string Name { get; protected set; }
    public string SSN { get; protected set; }
    public bool Active { get; protected set; }
    public string ActivatedBy { get; protected set; }
}