“THE INTERNET never forgets,” people say. But we are likely fooling ourselves about the permanence of our digital legacy, says Thomas S. Mullaney, a professor of history at Stanford University. In his new book, How We Disappear: A Personal History of Information, Mullaney says we might be losing track of important memories faster now than in the past.

What advice would you give about trying to gather the memories of a loved one who died?
You have to not be OK with the gaps. You need tenacity to keep looking for your loved one’s digital materials. But you also have to be able to stand in front of a historical record with more holes than Swiss cheese and be at peace.

How should we preserve digital photos?
I would prefer not to have my kids or grandkids have the same unnamed, confusing family photo albums I inherited. So maybe I would label these kinds of photos. I think that’s where we all can make decisions in life that extend into that kind of afterlife. —Terry Sullivan