Google servers create a PNG image of a chart from data and formatting parameters specified by a user's HTTP request.
The service supports a wide variety of chart information and formatting.
Users may conveniently embed these charts in a Web page by using a simple image tag.
Currently, line, bar, pie, and radar charts, as well as Venn diagrams, scatter plots, sparklines, maps, google-o-meters, and QR codes are supported.
Instead of creating the URL request manually, there are many open source libraries available for most programming languages.