Hi, I am designing an online shop website. It has a header, a top navigation, a left navigation, an area for displaying product information (an DIV called prod_div), and a footer. Right now, I an using javascript AJAX and PHP to refresh the prod_div so that other area stay put to give user a better browsing experience. The javescript call a PHP script, with connects to MySQL db and generate a webpage on the fly based on parameters passed to it. But the problem with this is that the back button will not work in cases that the user want to go back to the products he just viewed. What is an alternative for this?

Thanks for your help.

That's just how Ajax works. Since you haven't really left the page, there's nothing to click back to. There are solutions. If you search for 'ajax back button' or something similar you should see a lot of results.

Write the go back function yourself.
Use an array to record the history and put a "Go back" button in the page.On click the button,you can get the php page again use the data you stored.

Or leave a breadcrumb trail showing their path to the current page, not quite as good as an actual back button but maybe worth implementing.