Modus ponens

Modus ponens is a rule of inference in Propositional Logic, which says that if $p \rightarrow q$ is true and $p$ is true, then $q$ must also be true:

$p \rightarrow q$ $p$ $\therefore q$

For example: "If it's raining, the ground is wet. It's raining. Therefore, the ground is wet."

It's based on Implication, and is one of the simplest forms of a Valid Argument.