title: What does Box and Unbox mean?
body: <blockquote>
  <p><strong>Possible Duplicates:</strong><br />
  <a href="https://stackoverflow.com/questions/2111857/why-do-we-need-boxing-and-unboxing-in-c">Why do we need boxing and unboxing in C#?</a><br />
  <a href="https://stackoverflow.com/questions/13055/what-is-boxing-and-unboxing-and-what-are-the-trade-offs">What is boxing and unboxing and what are the trade offs?</a></p>
  </blockquote>
  
  <p>In C# what does &quot;Box and Unbox&quot; mean?</p>
  <p>Here's an extract from MSDN where I found the text.</p>
  <blockquote>
  <p>But this convenience comes at a cost.
  Any reference or value type that is
  added to an ArrayList is implicitly
  upcast to Object. If the items are
  value types, they must be boxed when
  they are added to the list, and
  unboxed when they are retrieved. Both
  the casting and the boxing and
  unboxing operations decrease
  performance; the effect of boxing and
  unboxing can be very significant in
  scenarios where you must iterate over
  large collections.</p>
  </blockquote>