In the Mass of Paul VI (OF = Ordinary Form) it is extremely rare throughout a liturgical year for incense to be used as compared to what is now the EF = Extraordinary Form of the Mass.
Explain to say one's children who know of only the Ordinary Form of Mass, what incense is and why it is used at Mass?
The questions are: what is incense, when and why is it used in either form of the Mass, are there rubrics in the Missal determining its use in either form of the Mass? What dictated the differences in its use from the EF to the OF of the Mass?