Antioxidants are substances that may support against cell damage, and are found in many foods, including fruits and vegetables. Antioxidants, do just as the name suggests, prevent or supports against the oxidation of cells, that without protection may lead to cellular damage. 

Good examples of antioxidants are,
 - Astaxanthin
 - Beta-carotene
 - Lutein
 - Lycopene
 - Selenium
 - Vitamin A
 - Vitamin C
 - Vitamin E

Vegetables and fruits are rich sources of antioxidants. There is good evidence that eating a diet with lots of vegetables and fruits is healthy and lowers risks of certain diseases.