title: Is it recommended to use simple CSS classes like .text-center?
body: <p>I'm learning HTML/CSS, and I've seen some examples like using <code>.text-center</code> for <code>text-align: center;</code> (in Bootstrap3).</p>
  
  <p>That is a little bit strange for me, because these classes' css style will never change, so I have to change their class when I need to change their style. For example, if I have to change an element with <code>class="text-center"</code> to <code>text-align: right;</code>, I'll change the class it uses to <code>class="text-right"</code> instead of changing class <code>text-center</code>'s style.</p>
  
  <p>Is there a detailed reason to use these fixed classes? </p>
  
  <p>If so what is the general rule for using/not using fixed classes?</p>