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copied!<p>The source of your confusion appears to be that there is a typo in the extract from C# station, which should read: "... except that the <strong>Equals</strong> works only on object instances. The ReferenceEquals method is static."</p> <hr> <p>You are loosely correct about the differences in the semantic meanings of each (although "different instances of the same object" seems a little confused, it should probably read "different instances of the same <em>type</em>) and about which can be overridden.</p> <p>If we leave that aside, let's deal with the last bit of your question, i.e. how they work with plain<code>System.Object</code>instances and <code>System.Object</code>references (we need both to dodge the non-polymorphic nature of <code>==</code>). Here, all three operations will work <em>equivalentally</em>, but with a caveat:<code>Equals</code>cannot be invoked on<code>null</code>.</p> <p><code>Equals</code>is an instance method that takes <em>one</em> parameter (which <em>can</em> be<code>null</code>). Since it is an instance method (must be invoked on an actual object), it can't be invoked on a <code>null</code>-reference.</p> <p><code>ReferenceEquals</code> is a static method that takes <em>two</em> parameters, either / both of which can be <code>null</code>. Since it is static (not associated with an object <em>instance</em>), it will not throw a<code>NullReferenceException</code> under any circumstances. </p> <p><code>==</code>is an operator, that, in this case (<code>object</code>), behaves identically to <code>ReferenceEquals</code>. It will not throw a<code>NullReferenceException</code>either.</p> <p>To illustrate:</p> <pre><code>object o1 = null; object o2 = new object(); //Technically, these should read object.ReferenceEquals for clarity, but this is redundant. ReferenceEquals(o1, o1); //true ReferenceEquals(o1, o2); //false ReferenceEquals(o2, o1); //false ReferenceEquals(o2, o2); //true o1.Equals(o1) //NullReferenceException o1.Equals(o2) //NullReferenceException o2.Equals(o1) //false o2.Equals(o2) //true </code></pre>

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