Diseases can be either communicable, which means they can be passed between individuals, or uncommunicable, which cannot. They are caused by pathogens like viruses, bacteria, protists, fungi or worms, environmental factors, genetics, or a combination. Pathogens are the agents that directly cause the disease, and can be transmitted by vectors like mosquitoes. Some notable diseases include HIV, influenza, malaria, tuberculosis, and diabetes. Lifestyle factors like diet, exercise, and avoiding toxins and bad health habits can impact disease risk, while vaccines, antibiotics, and general hygiene help prevent and treat diseases.