What is a disease? What are the further classifications of disease?

(N/A) disease is defined as a condition where the normal functioning of one or more organs or systems of the body is adversely affected,characterized by various signs and symptoms.
Any change from the normal state that causes discomfort or disability is called a disease.
Diseases can be broadly classified into two categories: infectious and non-infectious diseases.
$1$. Infectious diseases: These are diseases that can be easily transmitted from one person to another. They are very common,and everyone suffers from them at some point. Some infectious diseases,like $AIDS$,are fatal.
$2$. Non-infectious diseases: These are diseases that cannot be transmitted from an affected person to a normal,healthy person. Cancer is a major example of a non-infectious disease and is a leading cause of death. Additionally,drug and alcohol abuse also adversely affect our health.