Soap can mix with both water and with oil

Soap can mix with both water and with oil. The soap molecule has two different ends, one that is hydrophilic (polar head) that binds with water and the other that is hydrophobic (non-polar hydrocarbon tail) that binds with grease and oil.

When greasy dirt is mixed with soapy water, the soap molecules arrange themselves into tiny clusters called micelles. The oil-loving (hydrophobic) parts stick to the oil and trap oil in the center where it can't come into contact with the water. The soap also are made up of molecules and some were known to be hydrophilic.