Bootstrap Collapse

<button data-toggle="collapse" data-target="#demo">Collapsible</button>

<div id="demo" class="collapse">
Lorem ipsum dolor text....
</div>

<a href="#demo" data-toggle="collapse">Collapsible</a>

<div id="demo" class="collapse">
Lorem ipsum dolor text....
</div>

<div id="demo" class="collapse in">
Lorem ipsum dolor text....
</div>

<div class="panel-group">
  <div class="panel panel-default">
    <div class="panel-heading">
      <h4 class="panel-title">
        <a data-toggle="collapse" href="#collapse1">Collapsible panel</a>
      </h4>
    </div>
    <div id="collapse1" class="panel-collapse collapse">
      <div class="panel-body">Panel Body</div>
      <div class="panel-footer">Panel Footer</div>
    </div>
  </div>
</div>

<div class="panel-group">
  <div class="panel panel-default">
    <div class="panel-heading">
      <h4 class="panel-title">
        <a data-toggle="collapse" href="#collapse1">Collapsible list group</a>
      </h4>
    </div>
    <div id="collapse1" class="panel-collapse collapse">
      <ul class="list-group">
        <li class="list-group-item">One</li>
        <li class="list-group-item">Two</li>
        <li class="list-group-item">Three</li>
      </ul>
      <div class="panel-footer">Footer</div>
    </div>
  </div>
</div>

<div class="panel-group" id="accordion">
  <div class="panel panel-default">
    <div class="panel-heading">
      <h4 class="panel-title">
        <a data-toggle="collapse" data-parent="#accordion" href="#collapse1">
        Collapsible Group 1</a>
      </h4>
    </div>
    <div id="collapse1" class="panel-collapse collapse in">
      <div class="panel-body">Lorem ipsum dolor sit amet, consectetur adipisicing elit,
      sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad
      minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea
      commodo consequat.</div>
    </div>
  </div>
  <div class="panel panel-default">
    <div class="panel-heading">
      <h4 class="panel-title">
        <a data-toggle="collapse" data-parent="#accordion" href="#collapse2">
        Collapsible Group 2</a>
      </h4>
    </div>
    <div id="collapse2" class="panel-collapse collapse">
      <div class="panel-body">Lorem ipsum dolor sit amet, consectetur adipisicing elit,
      sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad
      minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea
      commodo consequat.</div>
    </div>
  </div>
  <div class="panel panel-default">
    <div class="panel-heading">
      <h4 class="panel-title">
        <a data-toggle="collapse" data-parent="#accordion" href="#collapse3">
        Collapsible Group 3</a>
      </h4>
    </div>
    <div id="collapse3" class="panel-collapse collapse">
      <div class="panel-body">Lorem ipsum dolor sit amet, consectetur adipisicing elit,
      sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad
      minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea
      commodo consequat.</div>
    </div>
  </div>
</div>