Q. Why do we need charoset?
A. Once charoset was an everyday food, though today it is limited to Pesach. The Mishnah (Pesachim 2:5) recognises that the ordinary recipe needed alteration on Pesach in order to omit the ingredient of flour.
The Pesach version came to symbolise the experience of the Israelite slaves, who made bricks with clay (similar in colour and texture to charoset) mixed with straw (recalled by the other substances mixed into the charoset).
It is not eaten on its own on Seder night but used as a dip, in sweet contrast to the bitter maror. It symbolises the dual motif of Pesach, the sourness of slavery and the sweetness of redemption.