A chart or graph gives an overview of the data variation in short and comprehensive way. It also reduces the time to grab the actual data fluctuations or variations and is available in visual form.
It is a diagram displaying the relationship between numbers or amounts. Common graphs use bars, lines, or parts of a circle to display data. Charts and Graphs are mainly used for statistics purpose and play a critical role in many applications.
Here are few tools which can build pretty good looking custom charts or graphs with defined statistics:
ProtoChart is a new opensource library using Prototype and Canvas to create good looking charts. This library is highly motivated by Flot, Flotr and PlotKit libraries.