Shingles is an infection caused by the chicken pox, varicella zoster virus. Even though it is the same virus, however, shingles generally erupts in a band on one side of the body, rather than all over the body.
After a patient has chickenpox, the varicella zoster virus lives in the nervous system and is never fully cleared from the body. Eventually, it may reactivate and travel along nerve pathways to your skin — producing shingles.
However for most cases of shingles, the cause for the reactivation of the virus is never found. But it may be due to lowered immunity to infections as you grow older. It is more common in older adults and in people who have weak immune systems.
About 20 percent of people who have had chickenpox are affected by zoster at a later part of their life. Have a look at some shingles pictures.