This is a duplicate of a post I made in one of the recent topics. I'm copying it here for easier reference as I send it to a couple friends.
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So what exactly is metadata?
Many years ago I was a telecommunications engineer for a large company and worked CALEA. For the uninitiated, that is law-enforcement wiretapping.
"All the people are so happy now, their heads are caving in. I'm glad they are a snowman with protective rubber skin" -- They Might Be Giants