Does jQuery traverse the DOM everytime we use $() to access the same element?

Question

After clicking the button, does jQuery traverse the DOM from the root again or is the child element cached? Will doing something like var childElement = $('.child') always make it possible to access the child element directly? Is saving a jQuery object in a variable practiced by developers?

$('button').click(function() {
  $('.child').append('Text. ');
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<button>Add text</button>

<div class="parent5">
  <div class="parent4">
    <div class="parent3">
      <div class="parent2">
        <div class="parent1">
          <div class="child">
          </div>
        </div>
      </div>
    </div>
  </div>
</div>