A remix is like when you take a bunch of Legos and build something new and cool using pieces from different sets. In a book remix, an author takes a story people already know and changes it up in a fun way. They might use the same characters, but put them in different situations or change the ending. It's like if you took a story about a prince and princess and turned it into a funny story about a frog and a squirrel. So, the remix is like a new version of a story that's different and exciting!