What does compressing do?

Answer:
Compressing means to apply pressure, but as someone else mentioned it really depends on what you're doing it to accomplish. Normally, it's to restrict the extravascular space such that hydrostatic pressure does not drive movement outward, resulting in bleeding, edema, etc.

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In relation to what?
Compression is putting pressure on something, as in a vein, to stop bleeding, bruising...depends on what you're actually talking about...
A "cold compress" can be either an ice pack, or a wet hand towel on the forehead....etc...
Need a bit more info there, sparky.

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Compressing a powder blend results in the production of a tablet, in pharmaceutical manufacturing.

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