<i> or <em>?

Question

They both show italic fonts. I know <em> = emphasis but would it be wrong to use <i> instead of <em>? Does it really matter?

<p> There are <em>fewer than one thousand</em>mountain gorillas who remain.</p>
or......
<p> There are <i>few than one thousand</i>mountain gorillas who remain.</p>

Answer 1

Does it really matter? Not for what you're using it for. However, I'd recommend using <em> before you use <i>. I'd also recommend that you use CSS before you use either of those also.

Answer 2

Much of HTML is semantic, which is useful for search engines and screen readers. In fact you could probably write a whole website with div tags with different class/ids targeted by different CSS formatting. Semantics is the key ;)

Answer 3

Thanks for the answers guys!