.wrap() .wrapAll() .wrapInner()

<div class="container">
  <div class="inner">Hello</div>
  <div class="inner">Goodbye</div>
</div>

$('.inner').wrap('<div class="new" />');

<div class="container">
  <div class="new">
    <div class="inner">Hello</div>
  </div>
  <div class="new">
    <div class="inner">Goodbye</div>
  </div>
</div>


$('.inner').wrapAll('<div class="new" />');

<div class="container">
  <div class="new">
    <div class="inner">Hello</div>
    <div class="inner">Goodbye</div>
  </div>
</div>


$('.inner').wrapInner('<div class="new" />');

<div class="container">
  <div class="inner">
    <div class="new">Hello</div>
  </div>
  <div class="inner">
    <div class="new">Goodbye</div>
  </div>
</div>