# Subset Notation

What is the difference between using ⊂ and ⊆? My book was not particularly lucid on this topic.

Depends on the author. Usually, the two notations mean the same thing, that is: $A\subset B$ or $A\subseteq B$ means that all elements in A are also in B.
Other authors (but a minority!) use $A\subset B$ to mean that A is a subset of B but A is not equal to B.