Parallel plots are best used when we need to compare many variables for each point and to understand the relationship between them, for example, if you need to compare an array of variables with the same attributes but differing values (for example, comparing motorcycle specs across different models).

Each connected line represents one data point. The vertical lines represent the columns or variables whose values have been plotted for each data point. The inflection point (marked in red) represents the values of those variables for those points. A parallel chart can be plotted very easily using pandas, as shown in the following code:

parallel = pd.plotting.parallel_coordinates(mtcars,'Category') 

This results in the following output: