When data value is dependent on the passing of time, a representation of the element of time must be included in the visualization. Time-based charts are the charts that animate a change in data values over a time period. Through this animation, the chart is able to graphically represent movement in values over time.
There are several time-reliant charts available through the Google Visualization API. At this time, they are the motion chart and the annotated timeline chart.
A motion chart is a visualization that animates the change in data over time. The data representation and animation of this chart can be displayed as three different chart types, bubble, bar, and line. The Size of the data point bubbles can also be set to represent additional data attributes. Colors, highlighted items, and motion tracking are also available as user control options on the chart.
Possibly the most important control of the Motion Chart is the button.
This button is self-explanatory...