system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can soap clean my hands off oily stuff like grease when soaps themselves are made largely of fat and oil?
gpt
Soaps aren't fats or oils. They're the product of *reacting* fats with alkaline substances, traditionally usually lye (sodium hydroxide). 

That reaction produces a molecule with two 'sides'. The original fat on one side repels water and attracts fats, and the extra base attached to the molecule on the other side attracts water. The combination means that soaps can help fats dissolve in water, by bonding to both the fats and the water.