In children's book terms, a margin is the area of white space that borders the content on a page, usually encompassing the top, bottom, and sides. Margins are crucial for enhancing the readability of the text and illustrations. Adequate margins help ensure that no important information is cut off during printing and binding. They also provide a visual break, making the page less cluttered and more appealing to young readers. Thoughtfully designed margins can contribute significantly to the overall aesthetic of the book.