So you know how when you get sick, you take medicine to feel better, right? Well, some people in the world get sick with really bad diseases like malaria or HIV/AIDS, and they don't have enough money to get the medicine they need to feel better.
That's where MassiveGood comes in! It's a program that helps these sick people by asking people who can afford it to donate just a little bit of money when they buy plane tickets or book a hotel room. That money then goes to help people who are sick get the medicine and treatment they need.
It's kind of like when you put some of your allowance into a piggy bank to save up for something you want. But in this case, the money goes to help people who really need it!