Middle Grade typically covers kids who are old enough to read on their own but aren't yet teenagers. Authors of MG books frequently (but not always) write YA books as well as MG.
"In 2016, I began writing the Tales of Mundane Magic series. It follows Gertie and Bridget Mallon through a world that has smart phones and laptops and cars, but with magic woven in. With their ghost dog Ziggy, their Pied-Piper-esque friend Ernest, and their necromancer-in-training bestie Vivien, the sisters give us a peek at everyday life in a magical world. In 2018 I self published Volume One, and now all four volumes are available anywhere books are sold!"