reference jqeury with php code example

Example 1: jquery script tag

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

// Put this script in the head of your index.html to load jQuery
// The Google Hosted Libraries is a stable, reliable, high-speed, 
// globally available content distribution network for the most popular, 
// open-source JavaScript libraries.

// Google works directly with the key stakeholders for each library effort 
// and accepts the latest versions as they are released.

Example 2: how to use jQuery

<html>
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <title>jQuery</title>
  </head>
  <body>
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.4/jquery.min.js"></script>
    <script>
      //jQuery code
    </script>
  </body>
</html>