Diseases can be sorted into two groups. A communicable disease is one that can be passed from one person to another, or from one organism to another. Communicable diseases are caused by pathogens. Cholera, tuberculosis, influenza and HIV are all communicable.
A non-communicable disease cannot be passed on from one person to another. It is not caused by a pathogen, so you cannot catch it from someone else. Examples include cancer, coronary heart disease and the inherited disorder cystic fibrosis.
Non-communicable diseases usually have other causes. These include a person's genes, their lifestyle, such as diet, smoking and lack of exercise, and the environment they live in.