Beginner Question(s): Understanding Turing Completeness



I'm having a hard time understanding Turing Completeness. I checked
out the Wikipedia article (http://en.wikipedia.org/wiki/Turing-
complete), but it seems kind of broad.

Does anyone out there have a concise definition for Turing
completeness?

Why is everybody so concerned about it?

How does it relate to the field of software development?

-Thx

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