Grief is a response to loss, particularly to the loss of someone or something that has died, for example the death of a parent, caregiver, sibling or grandparent is an experience they are faced with early in life.
Although primarily concerned with the emotional response to loss, it also has physical, behavioral, social, and philosophical dimensions. While the terms are often used interchangeably, bereavement refers to the state of loss, and grief is the reaction to loss.