The 1.x branch includes support for IE 6/7/8 and the 2.x branch does not.
https://code.jquery.com/jquery-1.12.1.js
https://code.jquery.com/jquery-1.12.1.min.js
https://code.jquery.com/jquery-2.2.1.js
https://code.jquery.com/jquery-2.2.1.min.js