1. The problem is to understand the difference between elements and sets. 2. In mathematics, a **set** is a collection of distinct objects, considered as an object in its own right. 3. An **element** (or member) is an individual object contained within a set. 4. For example, if we have a set $A = \{1, 2, 3\}$, then $1$, $2$, and $3$ are elements of the set $A$. 5. Important rules: - Elements are the objects inside a set. - Sets are denoted by curly braces $\{ \}$. - Elements can be anything: numbers, letters, other sets, etc. 6. To summarize: a set is a collection, and elements are the individual items inside that collection. This distinction is fundamental in set theory and many areas of mathematics.