Shingles, herpes zoster, is caused by the same virus that causes chickenpox. But people who have never had chickenpox do not get shingles.
After you have had chickenpox, the virus becomes dormant in the body. Years later, something awakens and reactivates it, only this time, it manifests as a different disease — a localized condition known as shingles.
Shingles can be intensely painful, but sometimes causes only mild pain and itchiness, along with the rash. In some cases, the pain persists for months after the rash is gone. It is usually confined to one area on one side of the body, typically on the chest, torso or around the eyes. Shingles can get into the eyes and cause problems.
Treatment with acyclovir or similar anti-viral drug can shorten the duration of the outbreak. You can get shingles twice, but it is rare. As to whether it is contagious, the answer is yes and no. Shingles itself is not contagious. But a person who has never had chickenpox can catch it from someone with shingles.