system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What's cholesterol and why is it good or bad for it to be high or low?

Asking for Ron Swanson.
gpt
Cholesterol is used by the body to build cells and transport nutrients.  So some is good and needed.  The problem comes from too much of the "low density" or LDL type.  This stuff is big and fluffy and has a tendency to get stuck in arteries and blood vessels.  This makes your heart have to pump harder and wears it out faster.