YA (Young Adult):
2009:
* The Hunger Games by Suzanne Collins: The dystopian novel that launched a global phenomenon.
* Shiver by Maggie Stiefvater: The first book in the "Raven Cycle" series, introducing readers to the captivating world of the Raven Boys.
* The Scorpio Races by Maggie Stiefvater: Another fantasy novel by Stiefvater, this one set on an Irish island with dangerous horse races.
* The City of Ember by Jeanne DuPrau: A post-apocalyptic adventure about children in a dying underground city.
* The False Prince by Jennifer A. Nielsen: The first book in a fantasy series about a boy who must pretend to be a long-lost prince.
* The Help by Kathryn Stockett: A powerful story about black maids in the American South in the 1960s, though aimed at adults, it garnered immense popularity with teens.
* The Lovely Bones by Alice Sebold: A moving and haunting novel about a young girl who is murdered and watches over her family from heaven.
2010:
* The Fault in Our Stars by John Green: A heartbreaking and ultimately hopeful story about two cancer patients who find love.
* Divergent by Veronica Roth: The first book in a dystopian series about a society divided into factions.
* Daughter of Smoke & Bone by Laini Taylor: A fantasy romance about a young woman who falls in love with an angel.
* The Hunger Games: Catching Fire by Suzanne Collins: The second book in the Hunger Games trilogy, raising the stakes and expanding the world.
* The Book Thief by Markus Zusak: A powerful story about a young girl in Nazi Germany who steals books.
* The Night Circus by Erin Morgenstern: A magical novel about two young magicians who fall in love.
* The Boy in the Striped Pajamas by John Boyne: A heartbreaking and poignant story about the Holocaust told through the eyes of a young boy.
Middle Grade (Ages 8-12):
2009:
* Diary of a Wimpy Kid: The Last Straw by Jeff Kinney: The third book in the popular "Diary of a Wimpy Kid" series.
* The Spiderwick Chronicles by Tony DiTerlizzi and Holly Black: A fantasy series about a family who discovers a world of fairies.
* The Chronicles of Narnia: The Magician's Nephew by C.S. Lewis: The prequel to the classic Narnia series.
* Wonder by R.J. Palacio: A moving story about a boy with facial differences who starts attending a mainstream school.
* The One and Only Ivan by Katherine Applegate: A heartwarming story about a gorilla who learns to read and write.
* A Wrinkle in Time by Madeleine L'Engle: A classic science fiction novel about a young girl who travels through time and space.
2010:
* Diary of a Wimpy Kid: Dog Days by Jeff Kinney: The fourth book in the "Diary of a Wimpy Kid" series.
* The Last Olympian by Rick Riordan: The fifth book in the "Percy Jackson & The Olympians" series.
* The Hunger Games: Mockingjay by Suzanne Collins: The third book in the Hunger Games trilogy.
* The Mysterious Benedict Society and the Perilous Journey by Trenton Lee Stewart: The second book in the "Mysterious Benedict Society" series.
* The One and Only Bob by Katherine Applegate: A heartwarming story about a dog who is determined to be a hero.
* The Graveyard Book by Neil Gaiman: A fantasy novel about a boy who is raised by ghosts in a graveyard.
These are just a few of the many wonderful books that were released in 2009 and 2010. To find more recommendations, you can browse online booksellers, check out book lists from librarians, and ask friends and family for their favorites.