HEALTH TOPICS 
Aging Overview
What Is It?
We all know the obvious signs of aging: wrinkles, gray hair, a slightly stooped posture, perhaps some "senior moments" of forgetfulness. But why do those things happen? What is aging?
Each of us is made up of cells—13 trillion of them. Our tissues and organs are each a bunch of cells, held together with various natural materials that the cells have made.
To continue reading this article, you must log in.
Subscribe to Harvard Health Online for immediate access to health news and information from Harvard Medical School.
- Research health conditions
- Check your symptoms
- Prepare for a doctor's visit or test
- Find the best treatments and procedures for you
- Explore options for better nutrition and exercise