Why is it considered to be such a big deal to have a 64-bit computer? Why does it "change everything?" Why do applications need to be designed differently between 32- and 64-bit platforms?

And, on OS X, how do you find which one you have!?

merged by Sathyajith Bhat Jun 6 '11 at 11:02

This question was merged with 32-bit vs. 64-bit systems because it is an exact duplicate of that question.

migrated from stackoverflow.com Jun 5 '11 at 16:39

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