Great work Shashank Sahay. I went through both of your articles. The articles very well explain each type of graph. Maybe in your next article, You can add the comparison of each chart to help people decide which chart to use in the given constraints.
For eg, The usage of the charts also depends on the type of variables. A bar chart is used when you have a discontinuous variable (for eg, no. of visitors vs sources) and line chart for a continuous variable (for eg, no. of visitors vs time).