What is .tpl.html files? (angularjs) : <p>I'm doing a angularjs blog tutorial, in the code example I see this new file type "<strong>tpl.html</strong>":</p>

<pre><code>$routeProvider
.when('/', {
templateUrl: 'views/post-list.tpl.html',
controller: 'PostListController',
controllerAs: 'postlist'
})
.when('/post/:postId', {
templateUrl: 'views/post-detail.tpl.html',
controller: 'PostDetailController',
controllerAs: 'postdetail'
})
.when('/new', {
templateUrl: 'views/post-create.tpl.html',
controller: 'PostCreateController',
controllerAs: 'postcreate'
});
</code></pre>

<p>What is this file type? Is different to html files?</p>
