By separating multiple selectors with a space, we can select descendant elements of an element, making the selectors more specific.

<html>
<head>
<style>p span {font-weight: bold;}</style></head><body><div class="box"></div><p><span>I'm in</span></p><ul><li><span>I'm not</span></li><li><span>I'm not</span></li></ul></body></html>
]]>

Fantastic! That way, we're selecting and styling every <span> element that's inside a <p> element.

As we inline elements can't contain block-level elements, does it really make sense to select every <p> element that's inside a <span> element?