The word plagiarism comes from a Latin word for kidnapping. You know that kidnapping is stealing a person. Well, plagiarism is stealing a person's ideas or writing. You wouldn't take someone's lunch money or bike, right? Well, someone's words and thoughts are personal property, too. (kidshealth) To be on the safe side, always make it clear where the information comes from. Your teacher will tell you how to do this.
Below is a short video with more information about plagiarism!