1. Many websites are introduced in this way, and the customer's browser may have cached jquery. You can directly call the local one, which is faster...
2. Google code uses CDN technology to have node servers in many places. When loading jquery, it will never be slower than loading on your server, except for the local server: )
3. It can save server traffic and reduce server bandwidth pressure
You can use two ways to reference jquery of google code
1. Reference http://www.google.com/jsapi?key=Goolge key
2. Direct Reference address http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js
jQuery 1.2.6 Reference file