Shingles is a viral infection caused by the same virus that causes chickenpox (varicella virus). Anyone who has had chickenpox can get shingles, but it is most common over age 50. A person can get shingles more than once.
Shingles causes a painful rash with localized blisters. While the condition is not contagious, it is possible to pass chickenpox to another person if they are in contact with fluid from the blisters, which is why people with shingles should cover their rash until the blisters crust over.