All 10 Equality: Equals, GetHashCode & IEquatable questions
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How does a struct's default Equals() behavior differ from a class's, even without any overrides? How do you correctly override Equals() and GetHashCode() together on a class, and why must they always be overridden as a pair? How does implementing IEquatable<T> improve on just overriding Equals(object), and why is it recommended alongside the override? How does HashCode.Combine() help you write a correct and well-distributed GetHashCode() implementation? Why is it critical that GetHashCode() only depend on IMMUTABLE fields, and what bug occurs if you violate this rule? How does record type equality work by default, and how does it differ fundamentally from a regular class's default equality? How should Equals() be implemented differently for a class designed to support INHERITANCE, to correctly handle equality between a base type and derived types? How do you correctly implement IComparable<T> alongside IEquatable<T>, and what consistency rule must they both satisfy together? How does structural (deep) equality for collections work, and why doesn't List<T>.Equals() perform element-by-element comparison by default?
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C# › Equality: Equals, GetHashCode & IEquatable

What is the difference between reference equality (==) and value equality (Equals()) for a reference type by default?

Beginner

Answer

For a reference type without overrides, both == and the inherited Object.Equals() check REFERENCE equality — whether two variables point to the exact SAME object in memory — not whether their content/data is logically equivalent.
var p1 = new Point(1, 2);
var p2 = new Point(1, 2);
Console.WriteLine(p1 == p2);       // False -- different objects, same data
Console.WriteLine(p1.Equals(p2));  // False -- same, unless Equals is overridden
Real-world example Understanding why two 'identical-looking' objects don't compare as equal until you explicitly define value equality.

Common follow-ups: How does this default behavior differ for value types like struct?

Value vs Reference Types
All 10 Equality: Equals, GetHashCode & IEquatable questions