title: GetHashCodes - how and when it is used?
body: <p>How should good overriden <code>GetHashCode</code> method look like? (for instance for a pure model class which contains three string properties) Are there any common principles / schemats in writing such methods?  Where it is exactly used (besides HashTables/Dictionaries) ? Is it a good idea to rely on hash code when we're comparing object equality?</p>