 <p>It is a formatted string where <code>%s</code> is a placeholder. I suspect that $sql is handed to <a href="http://php.net/sprintf">sprintf</a> to transform it into a real query. Example:</p> <pre><code>$name = 'posts'; $sql = "SELECT * FROM page_table WHERE page_name = '%s' LIMIT 1"; $formattedSql = sprintf($sql, $name); </code></pre> <p>This will generate a query looking like:</p> <pre><code>SELECT * FROM page_table WHERE page_name = 'posts' LIMIT 1 </code></pre> <p>This is very useful when you don't want to fiddle around with quotes and doublequotes.</p>