Time series data is data that is measured using a sequence of certain points at particular times. The Dow Jones Index is an example of data that is measured using time series data, as the data collected is listed at a certain time on each day. Line charts are used to plot time series data and these enable the viewer of the data to analyze the data with ease, and to compare and contrast the differences between one set of data at a particular time and another set of data at a particular time.