To whom and for what reason are summer and winter gifts given?

Both are gifts to those who have taken care of the sender and are given to express gratitude to teachers, go-betweens, company supervisors, business clients, tutors, relatives, faraway parents, and others.
Chugen, the word for summer gifts, literally means July 15, so it is appropriate to send them around the first part of July to about the 15th.
Winter gifts should be delivered between early December and December 20.
When expressing gratitude once a year, the winter gift is sufficient.