Contagious diseases can spread to others through many forms. Four types of infectious disease transmission can happen: (1) contact transmission, which can be through direct physical contact (2) vehicular transmission, which involves contaminated objects, (3) airborne transmission, which involves spread of infectious particles through air, and (4) vector transmission, which is spread through insects or animals. Since diseases can spread through many forms of transmission it is important for people who are not infected to stay at home so that they won't get sick. For those who are sick then it is important for them to quarantine to make sure they don't spread the disease.