ELI5: How do scientists able to create liquid nitrogen? explainlikeimfive

I believe they use a related process in refrigerators, but how are they able to get a refrigerant stable enough to cool it that much, where do they get the nitrogen from, and how are they able to purify it to be just nitrogen and not a mix of gasses?

edit: I just realized I typed my question like a literal five year old.

Submitted April 18, 2016 at 06:37AM by Timmitei http://ift.tt/1SlE0KU explainlikeimfive