Pathogen

Pathogen explained in an easy to understand way:

Imagine when you're hosting a party, and an uninvited guest sneaks in, disrupting the mood and causing chaos. Similarly, a pathogen is like that unwelcome intruder in your body, such as a bacteria, virus, or parasite, that causes disruption and illness. Just as the uninvited guest can spoil the party for everyone, a pathogen invades our body's environment, creating problems and spreading its effects, much like how a single unruly guest can impact the entire gathering.