Why does puss come out of pimples?

Answer 1

That's just plasma. It's like a bonding agent of blood. It contains little platelets that help hold skin together while healing and making newer skin (if it's white then it's pus). Plasma is also the same thing that heals a cut if you skin your knee or get scrached by a cat.

Answer 2

White puss is largely made up of white blood cells that enter the pimple to clean the area of bacteria.

Answer 3

It I oil