This last stage, referred to delicately as late adulthood or maturity, or less delicately as old age, begins sometime around retirement, after the kids have gone, say somewhere around 60. Some older folks will protest and say it only starts when you feel old and so on, but that's an effect of our youth-worshipping culture, which has even old people avoiding any acknowledgement of age. In Erikson's theory, reaching this stage is a good thing, and not reaching it suggests that earlier problems retarded your development!
The task is to develop ego integrity with a minimal amount of despair. This stage, especially from the perspective of youth, seems like the most difficult of all. First comes a detachment from society, from a sense of usefulness, for most people in our culture. Some retire from jobs they've held for years; others find their duties as parents coming to a close; most find that their input is no longer requested or required.
Then there is a sense of biological uselessness, as the body no longer does everything it used to. Women go through a sometimes dramatic menopause; Men often find they can no longer "rise to the occasion." Then there are the illnesses of old age, such as arthritis, diabetes, heart problems, concerns about breast and ovarian and prostrate cancers. There come fears about things that one was never afraid of before -- the flu, for example, or just falling down.
Along with the illnesses come concerns of death. Friends die. Relatives die. One's spouse dies. It is, of course, certain that you, too, will have your turn. Faced with all this, it might seem like everyone would feel despair.
In response to this despair, some older people become preoccupied with the past. After all, that's where things were better. Some become preoccupied with their failures, the bad decisions they made, and regret that (unlike some in the previous stage)