According to freud, which part of everyone's personality operates according to the "pleasure principle"?

According to Freud, the part of everyone's personality which operates according to the 'pleasure principle' is id.
Id, meaning it in Latin, is the part of our mind which works according to what we want and consciously desire. It refers to our primal and bodily needs, such as the need to sleep, drink water, have sex, etc. The other structures are ego (the reality principle), and superego (the moral principle).