What is this plastic appliance for my teeth?

Hello, My name is Matthew. I'm 12. My dentist told me that they would need to install a plastic appliance for my teeth in two weeks. I need this appliance because one of my teeth are not straight. The dentist said it would straight it out. I want to know if this would be painful to put on and take off plus I would like to know what it looks like. If you can please give me a link to a picture if you can. Thank You!|||It's like the new braces probably, really cool and painless