Why do we need to write read graphs

We need to analyse and to extract the essence from the raw material-the graphs.
Before writing anything,our purpose should be clear,that is to analyse to to make use of the processed information.
I read some essay writing guide just now.
We should write about what worth mention,we should write about the stark contrast,the plunge and sudden increase.
Essay writing should has its clear purpose within itself.It should not be dead,should not follow a certain module written by some not-so-authentic people.