An epidemic is a rapidly increasing and actively spreading disease cases in a specific geographical area, such as a community, population, or region. It does not necessarily have to be infectious or contagious. An epidemic can progress into a pandemic if it gets out of control and spreads globally.

A pandemic is an epidemic that is widespread across multiple countries or continents, and generally in an uncontrolled manner. It is typically declared by the World Health Organization.

Endemic is when a disease is consistently present but in a manner where the spread, rates are predictable and not uncontrolled. An endemic disease can lead to an outbreak.

An outbreak is a greater than expected increase in the number of endemic cases. An outbreak can turn into an epidemic if not controlled quickly.