# Symbols:Set Theory/Subset

## Subset

$\subseteq$

$S \subseteq T$ means $S$ is a subset of $T$.

In other words, every element of $S$ is also an element of $T$.

Note that this symbol allows the possibility that $S = T$.

The $\LaTeX$ code for $\subseteq$ is \subseteq .

## Deprecated Symbols

### Subset

$\subset$ is sometimes used to mean:

$S$ is a subset of $T$

in the sense that $S$ is permitted to equal $T$.

That is, for which we have specified as $S \subseteq T$.

Although many sources use this interpretation, it is emphatically not recommended, as it can be the cause of considerable confusion.