What is Zakat al-Fitr, and why is it obligatory for young children?

Zakat al-Fitr is related to bodies and individuals, so it is obligatory upon young children for their purification. This is because it became obligatory upon creation as a purification of the soul and a development of its knowledge. It was named thus because of its obligation due to breaking the fast (fitr), and it is also said that it comes from "fitra" (innate disposition/creation) due to its relation to bodies.