present perfect vs past perfect

In the present perfect, our reference point is the present. You use the present perfect about a something that started in the past and continues into the present: (At this time) I have known her for six years. I have lived in London for five years. I have not smoked for two weeks.

In the past perfect, our reference point is in the past. You use the past perfect about something which happened before a time in the past. I had known her for six years when she married Joe. He had visited Japan three times when reached the age of 30. She had seen three cats by the time she arrived at school.