What is a disease? How many types of diseases have you studied? Give examples.

(N/A) disease is a condition in which the normal functioning of the body or a part of it is impaired or disturbed, leading to adverse effects on health.
Types of diseases:
$1$. Acute Diseases: These are diseases that last for a very short period. Examples: $\text{Common cold}$, $\text{influenza}$, $\text{fever}$.
$2$. Chronic Diseases: These are diseases that persist for a long time, sometimes even for a lifetime, and have long-term adverse effects on health. Examples: $\text{AIDS}$, $\text{tuberculosis}$, $\text{diabetes}$.
$3$. Infectious (Communicable) Diseases: These diseases are caused by pathogens and can spread from an infected person to a healthy person. Examples: $\text{Malaria}$, $\text{typhoid}$, $\text{cholera}$.
$4$. Non-infectious (Non-communicable) Diseases: These diseases do not spread from an infected person to a healthy person. They are often caused by lifestyle factors, genetic disorders, or metabolic issues. Examples: $\text{Cancer}$, $\text{hypertension}$, $\text{arthritis}$.
Non-infectious diseases can be further categorized into:
$(a)$ Lifestyle Diseases: $\text{Diabetes}$, $\text{hypertension}$.
$(b)$ Genetic Diseases: $\text{Haemophilia}$, $\text{sickle-cell anemia}$.