What is a memory? I had not thought about this question from a physiological standpoint until I read Connectome: How the Brain’s Wiring Makes Us Who We Are by Sebastian Seung. This book describes memories as a series of connections between neurons in our brain. These connections make up our connectome. The connectome provide one possible explanation for understanding how we process and retain memories. In addition, it explains what happens when we cannot remember. Forgetfulness happens when the neural connections corresponding to a particular memory are weakened or lost entirely.
Here’s where photographs and other links to past events can help. They reinforce neural connections corresponding to past events. So, the next time you take a photograph think of it not as a snapshot, but instead as a direct link to new neural connections. Similarly, scrapbooks and photo books are more than photos. They are a link to our connectome and our memories, and this link is the reason why it so important to preserve our photos and our past.
All About Images Blog 
Msrk, thank you for this important message.