Genres
Middle grade fiction
Literature intended for children between the ages of 8 and 12, sitting below young adult fiction, with strict content conventions of its own.
Middle grade fiction is literature intended for children between the ages of 8 and 12, as Wikipedia's article defines the category. It sits above picture books, easy readers and chapter books, which serve younger readers, and below young adult fiction, the category for readers aged 12 to 18. The conventions are explicit: no profanity, no romance past kissing, no realistic violence (fantasy violence is the accepted form), and stories that tend to focus on the characters' friends, family and immediate surroundings. Charlotte's Web, Percy Jackson and the Olympians and the early Harry Potter books are named examples, and most Newbery Medal winners have been middle grade titles.
For a writer the category is a contract rather than a suggestion: the content lines are promises made to parents and librarians, and word counts run shorter than YA's. The commonest mislabeling in drafts is calling a ten-year-old protagonist's story YA; if the hero is eight to twelve, the shelf is middle grade. See how long is a novel for where the length bands sit.