I have been working with R for 8 months and this weekend finally learned about the Levels Function. The levels function is important because it lets you control the order of categorical variables in a display other wise R will order by alphabet. This is especially helpful with charts.
I wish I had a better visual example but R hacking and problem solving did not lead to great documentation.
Additional Resources to help with factoring and levels in R: UCLA Institute for Digital Research and Education.