The new Google Chart Tools is a Javascript library that lets the user create interactive graphs and charts. Google calls it their 'Visualization API', and differentiates it from the older 'Chart API' by saying their new tool is interactive, uses live data, and lets you incorporate third-party tools into your applications. I will call it their Chart Tool, because that is what it is called on the title page as of the writing of this document.
This example shows how to create a multi-line line graph using Google Chart Tools, PHP, and AJAX.