An outbreak is when a lot of people start getting sick from the same thing at the same time. It's like when you and your friends all get the flu or a cold around the same time.
It can happen with many different sicknesses, like illnesses that spread from person to person, like the flu or the common cold. It can also happen with infections that are caused by bacteria, like E. coli or Salmonella, or viruses, like Zika or Ebola.
When doctors notice that a lot of people are getting sick with the same thing at the same time, they investigate to try to figure out why it is happening, and how to stop it from spreading. They might ask questions, take samples, or do tests to try and find out where the sickness is coming from.
During an outbreak, it's very important to be careful and take precautions to prevent getting the sickness yourself or spreading it to others. This can include things like washing your hands often, covering your mouth and nose when you cough or sneeze, and staying home from school or work if you feel sick. And remember, always listen to the advice of doctors and medical professionals to keep yourself and others safe!