system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do fridges work? How can energy be used to make something colder than it's surroundings?

It's been bothering me for a solid five minutes.
gpt
Your intuition is right: you can easily transform energy into heat, but you can't transform energy into cold.  What you can do, though, is use energy to **move heat around.**  What a fridge does is take heat from the insulated inside and release it in the back.

Your next question may be: how do you take heat from the inside of a fridge when it's colder than ambient temperature?  Here's the gist of it: it uses a property of compression.  

You may have noticed that a bicycle pump gets warm when you use it.  It's not just due to friction, it's also because compressing air makes it warmer.  On the opposite, a spray can gets cold when you use it.  That's because you're releasing pressure, and that makes it colder.

So a fridge use these principles of compression: there's a fluid that goes through the radiator in the back, then through the insulated inside.  When it's in the radiator, it's compressed so that it gets hotter and will lose some of its heat to the air around it.  Then it goes inside where it is decompressed, which makes it colder and able to take more heat.