Can I use a header tag in footer inside section? I want to know if I can use a header tag in footer inside section.  I also want to know if this follows SEO.

For example, I made four section boxes in footer:

&lt;footer&gt;
&lt;div class="ftr_top"&gt;&lt;img src="media/footer.png"&gt;&lt;/div&gt;
&lt;div class="ftr_bottom"&gt;
&lt;section class="ftr_section"&gt;
&lt;header class="ftr_head"&gt;
&lt;h3&gt;Box 1&lt;/h3&gt;
&lt;/header&gt;
&lt;ul&gt;
&lt;li&gt;&lt;/li&gt;
&lt;li&gt;&lt;/li&gt;
&lt;li&gt;&lt;/li&gt;
&lt;/ul&gt;
&lt;/section&gt;
&lt;section class="ftr_section"&gt;
&lt;header class="ftr_head"&gt;
&lt;h3&gt;Box 2&lt;/h3&gt;
&lt;/header&gt;
&lt;ul&gt;
&lt;li&gt;&lt;/li&gt;
&lt;li&gt;&lt;/li&gt;
&lt;li&gt;&lt;/li&gt;
&lt;/ul&gt;
&lt;/section&gt;
&lt;section class="ftr_section"&gt;
&lt;header class="ftr_head"&gt;
&lt;h3&gt;Box 3&lt;/h3&gt;
&lt;/header&gt;
&lt;ul&gt;
&lt;li&gt;&lt;/li&gt;
&lt;li&gt;&lt;/li&gt;
&lt;li&gt;&lt;/li&gt;
&lt;/ul&gt;
&lt;/section&gt;
&lt;/div&gt;
&lt;/footer&gt;
It's not valid HTML5 to have a &lt;header&gt; element inside a &lt;footer&gt; element. You could have checked this yourself on this site:

http://validator.w3.org/check

For using &lt;header&gt;, &lt;footer&gt; and &lt;section&gt; correctly, see this page:

https://developer.mozilla.org/en-US/docs/Web/HTML/Element/footer

For even more technical details, see the HTML5 specification:

http://www.w3.org/TR/html5/sections.html#the-footer-element

Special thanks to @amon for the links!