A clinical trial is an experiment where a doctor or scientist tests a medicine or treatment to see if it is safe and works well. They may test medicines on animals first but they need to test it on people too. In a clinical trial, people volunteer to take the medicine or treatment. The people in the trial are split into two groups. One group will take the medicine and the other group will take a fake medicine or a different kind of treatment. This helps the doctor or scientist compare how the people who took the medicine feel and if the medicine has any side effects. If the medicine they test works very well, they might make it available to everyone.