\emph{terms}: Terms talk about objects, they are elements of the domain: individual objects like Alice or Bob, variables since they represent objects like $x, y$, function symbols since they refer to objects like $m(x)$ or $x+y$\\ \\
\emph{formulas}: Formulas have a truth value. Each predicate is a formula, e.g. $S(x)$, $P(x)$, $\forall x \big(S(x) \imp P(x) \big)$ 