Varicella zoster is a virus that causes two distinct diseases: chickenpox and shingles. Chickenpox is typically a childhood illness characterized by an itchy rash and flu-like symptoms. It spreads easily through respiratory droplets or direct contact with the rash. After a person recovers from chickenpox, the virus remains dormant in the body. Later in life, it can reactivate as shingles, causing a painful rash and other symptoms. Vaccines are available to prevent both chickenpox and shingles, significantly reducing the incidence and severity of these diseases.