 <p>When used as part of a URL, ? and &amp; represent key value pairs that make up the Query String, which is a set of information sent to the server.</p> <p>The query string starts after the end of the page being requested with a ? and then a key value pair like:</p> <pre><code>?variable1=value1 </code></pre> <p>Any additional key/value pairs need to be prefaced with &amp; like:</p> <pre><code>?variable1=value1&amp;variable2=value2&amp;variable3=value3 </code></pre>