The teaching that lies under the practice is that a person selects their ori, the inner head that carries their destiny, before birth, and then arrives without any memory of the choice. Life is therefore partly a matter of getting back into alignment with an agreement one has already made. Ori veneration is the ordinary corrective for a misalignment: it is done before something is undertaken, at a change of circumstance, or when matters have gone wrong for long enough to suggest the problem is not circumstantial.
The act is called bori or ibori, which means simply to feed the head. Prayers are addressed to a person's own ori, praise names are recited to it, and prescribed materials are applied to the crown. It can be done by the person alone, and it can be done for them by a priest, and a diviner may prescribe it as the answer to a reading.
The unusual thing about it is the direction it faces. Almost every other act in the tradition is addressed outward, to an orisha, to the ancestors, to Olodumare. This one is addressed to a component of the worshipper. Yoruba writers have made a good deal of the resulting proposition, that a person's own ori is closer to them and more consequential for their life than any orisha, and that no orisha can do for a person what their own ori will not sanction.