In C#, use of value types vs. reference types

Question

My questions are:

• When should we use value types and when reference types?
• What are the advantages and disadvantages of one over other?
• What if one uses reference types everywhere? Is there any harm in it?

Please also discuss advantages and disadvantages of each one. I want to understand that as well.

Answer 1

You should use value types for small, immutable types which represent values.
Never make mutable structs.

For everything else, use reference types.

Answer 2

Use value types for immutables that do not have an identity of their own (a 1 is a 1), use reference types for other things.