An equilateral triangle oriented so the base is parallel to the bottom of the screen. The word "time" is written in the centre of the triangle. Outside of the triangle at the top point, the word "host" is written. Outside of the triangle at the bottom right point, the word "environment" is written. At the final point on the left hand side, outside of the triangle, the word "agent" is written. This is to communicate that host, agent, and environmental factors, along with time, interplay to create illness.