revision:
The <em> tag marks/defines text that has emphasis. The <em> element can be nested, with each level of nesting indicating a greater degree of emphasis. The content inside is typically displayed in italic. A screen reader will pronounce the words in <em> with an emphasis, using verbal stress.
<em> . . . </em>
Get out of bed now!
code: <p class="spec">Get out of bed <em>now</em>!</p>
We had to do something about it.
code: <p class="spec">We <em>had</em> to do something about it.</p>
This is not a drill!
code: <p class="spec">This is <em>not</em> a drill!.</p>
In HTML 5, what was previously called block-level content is now called flow content.
code: <p class="spec">In HTML 5, what was previously called <em>block-level</em> content is now called <em>flow</em> content.</p>