HTML 코드 작성 표준은 무엇입니까?

<img src="images/google.png" alt="Google">  
<input type="text" name="title">   
<ul>  
  <li>Style</li>  
  <li>Guide</li>  
</ul>  
<!-- Not recommended -->  
<span class="avatar">  
  <img src="...">  
</span>  
<!-- Recommended -->  
<img class="avatar" src="...">

<!-- Not recommended -->  
<div class="j-hook left contentWrapper"></div>   
<!-- Recommended -->  
<div id="j-hook" class="sidebar content-wrapper"></div>

<a id="..." class="..." data-modal="toggle" href="###"></a>  
  
<input class="form-control" type="text">  
  
<img src="..." alt="...">