HTML5 semantic layout (div, article, section) and explicit identifiers I'm writing a markup for: 

And I've split it for these sections:

&lt;header&gt;
    &lt;div id="logo"&gt;&lt;/div&gt;
    &lt;nav id="mainNav"&gt;&lt;/nav&gt;    
&lt;/header&gt;
&lt;div id="banner"&gt;&lt;/div&gt;
&lt;div id="content"&gt;
    &lt;section id="advantages"&gt;
        &lt;section class="advantage"&gt;&lt;/section&gt;
        &lt;section class="advantage"&gt;&lt;/section&gt;
        &lt;section class="advantage"&gt;&lt;/section&gt;
        &lt;section class="advantage"&gt;&lt;/section&gt;
    &lt;/section&gt;
    &lt;div id="main"&gt;&lt;/div&gt;
    &lt;aside&gt;&lt;/aside&gt;
&lt;/div&gt;
&lt;footer&gt;
    &lt;div id="extra"&gt;
        &lt;article class="extra"&gt;&lt;/article&gt;
        &lt;article class="extra"&gt;&lt;/article&gt;
        &lt;article class="extra"&gt;&lt;/article&gt;
        &lt;article class="extra"&gt;&lt;/article&gt;
    &lt;/div&gt;
    &lt;div id="credit"&gt;&lt;/div&gt;
&lt;/footer&gt;


Is it semantically correct(div, section, article) and are my identifiers explicit?
#logo → h1

Your &lt;div id="logo"&gt;&lt;/div&gt; should be a h1, otherwise the document outline wouldn't be correct:

&lt;h1&gt;&lt;img id="logo" src="logo.png" alt="Progress Business Company"&gt;&lt;/h1&gt;


See https://stackoverflow.com/a/14920215/1591669 for an explanation.

#banner → header or aside

If your &lt;div id="banner"&gt;&lt;/div&gt; doesn't contain main content, it should go in an aside element, or, if it can be understood as part of the header (probably on each page of the site), in the header element.

#main → section (or article)

Instead of &lt;div id="main"&gt;&lt;/div&gt; you could use a sectioning element here. I assume your div contains a heading ("Welcome, dear visitor!"), so you have something like an implict section anyhow. Why not make it explicit? So use a section instead of the div (depending on the actual content, article might be suitable instead).

#content &gt; aside → section

I'd say on the front page the testimonials could be considered part of the main content (in the end it depends on the real content/context), so instead of aside you could use section then.

Each single testimonial should be in its own article, of course.

#extra &gt; article → section

I don't think article elements in the footer are suitable for that kind of content (unless your actual page contains something different). (Only the newsletter form could possibly get article instead of section, but that's not that clear; personally I'd use section for it, too).

So, I'd go with section here. If the contact details listed under "Address" are relevant for the whole page, you should use the address element, too.

&lt;div id="extra"&gt;
    &lt;section class="extra"&gt;&lt;/section&gt;
    &lt;section class="extra"&gt;
      &lt;h1&gt;Address&lt;/h1&gt;
      &lt;address&gt;…&lt;/address&gt;
    &lt;/section&gt;
    &lt;section class="extra"&gt;&lt;/section&gt;
    &lt;section class="extra"&gt;&lt;/section&gt;
&lt;/div&gt;