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The movie Interstellar does a decent job demonstrating this (well the gravity piece anyway with the proximity to black holes).

I also think satellite clocks have to take time relativity it into account (both due to distance from earth's gravity and their speed).

Randall Munroe has a pretty entertaining write up that does a decent job giving a high level overview in pretty easy to understand terms: http://www.newyorker.com/tech/elements/the-space-doctors-big...