Giving someone gifts, whether it happens to be for a special occasion like a holiday or a birthday, or at a random time for no particular event, is a show of affection and also a show of materialism. Why are these two linked? Why is it necessary to give a thing to someone?
Why do we give gifts?
Related questions: Why do we like to receive gifts? What are our responsibilities to others? Why do we feel the need to belong? How can we maintain wonder?