The superset operator in set theory is denoted using the superset symbol which looks like a U turned ninety degrees counter clockwise with a horizontal line underneath.
A proper superset is denoted by the superset symbol which looks like a U rotated ninety degrees to the left.
The subset operator is denoted using a U shapes symbol rotated ninety degrees to the righ with a horizontal line underneath.
A proper subset is denoted by the symbol ⊂