What is the difference between include and block in Twig?
<p>I'm trying to make a bootstrap theme for <a href="http://philecms.com" rel="nofollow">PhileCMS</a> which uses Twig. Right now I'm working on the menu. I've been searching to find out how to make a page active, and I've been seeing stuff about blocks. Right now my index.html looks something like this</p>

<pre><code>{% include 'header.html' %}
&lt;body&gt;
{% include 'nav.html' %}
&lt;div class="container"}
{{ content }}
{% include 'footer.html' %}
</code></pre>

<p>My nav.html looks something like this:</p>

<pre><code>&lt;div class="header clearfix"&gt;
    &lt;nav&gt;
      &lt;ul class="nav nav-pills pull-right"&gt;
        &lt;li role="presentation"&gt;&lt;a class="{% if app.request.attributes.get('_route') starts with 'home' %}active{% endif %}"&gt;Home&lt;/a&gt;&lt;/li&gt;
        &lt;li role="presentation"&gt;&lt;a class="{% if app.request.attributes.get('_route') starts with 'about' %}active{% endif %}"&gt;About&lt;/a&gt;&lt;/li&gt;
        &lt;li role="presentation"&gt;&lt;a class="{% if app.request.attributes.get('_route') starts with 'contact' %}active{% endif %}"&gt;Contact&lt;/a&gt;&lt;/li&gt;
      &lt;/ul&gt;
    &lt;/nav&gt;
    &lt;h3 class="text-muted"&gt;{{ site_title }}&lt;/h3&gt;
&lt;/div&gt;
</code></pre>

<p>Is this proper coding practice, or should I be doing something with  blocks? I don't really understand how blocks work.</p>