Что делает \ (обратная косая черта) в PHP (5.3+)?

// Clean svg content (if you want to update the svg's objects)
// Note : .html('') doesn't works for svg in some browsers
$('#svgObject').empty();
// add some objects
$('#svgObject').append('<polygon class="svgStyle" points="10,10 50,10 50,50 10,50 10,10" />');
$('#svgObject').append('<circle class="svgStyle" cx="100" cy="30" r="25"/>');

// Magic happens here: refresh DOM (you must refresh svg's parent for Edge/IE and Safari)
$('#svgContainer').html($('#svgContainer').html());

.svgStyle
{
  fill:cornflowerblue;
  fill-opacity:0.2;
  stroke-width:2;
  stroke-dasharray:5,5;
  stroke:black;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<div id="svgContainer">
  <svg id="svgObject" height="100" width="200"></svg>
</div>

<span>It works if two shapes (one square and one circle) are displayed above.</span>