css: what does '>' sign mean between two elements ? : <p>For example, in this code: </p>

<pre><code>tr:last-child&gt;td:first-child {
    -webkit-border-radius: 0 0 0 25px;
    border-radius: 0 0 0 25px;  
}
</code></pre>

<p>'tr:last-child' means the last element of type tr. 'td:first-child' means the last element of type td. What does the '>' sign between them mean? </p>
