 Sometimes we write or speak a sentence \(S\) that expresses nothing either true or false, because some crucial information is missing about what the words mean. If we go on to add this information, so that \(S\) comes to express a true or false statement, we are said to interpret \(S\), and the added information is called an interpretation of \(S\). If the interpretation \(I\) happens to make \(S\) state something true, we say that \(I\) is a model of \(S\), or that \(I\) satisfies \(S\), in symbols ‘\(I \vDash S\)’. Another way of saying that \(I\) is a model of \(S\) is to say that \(S\) is true in \(I\), and so we have the notion of model-theoretic truth, which is truth in a particular interpretation. But one should remember that the statement ‘\(S\) is true in \(I\)’ is just a paraphrase of ‘\(S\), when interpreted as in \(I\), is true’; so model-theoretic truth is parasitic on plain ordinary truth, and we can always paraphrase it away.