Shingles is an infection that is caused by the same virus that causes chickenpox. You can only get shingles if you've had chickenpox in the past (usually as a child). Shingles is also called herpes zoster. It is most common in people over 50 years of age, but young people can get it as well.
After you recover from chickenpox, the virus stays in your body. It moves to the roots of your nerve cells (near the spinal cord) and becomes inactive (dormant). Later, if the virus becomes active again, shingles is the name given to the symptoms it causes.
It is not known what exactly causes the virus to become active again, but there are several possibilities:
You can't catch shingles from someone else. However, if you've never had chickenpox, you may get chickenpox from close contact with someone who has shingles because the blisters contain the chickenpox virus.