What is "magyk"

Magyk (Mag-ike) is a fantasy novel by Angie Sage. It is the first book in the seven-book Septimus Heap series. The sequel, Flyte was released in March 2006, Physik in March 2007, Queste in 2008, Syren in September 2009, Darke in July 2011, and Fyre in 2013. The book cover of Magyk alludes to the diary that the ExtraOrdinary Wizard Marcia makes for her apprentice, Septimus Heap. The cover also depicts Septimus's Dragon Ring, rendered as if it were sitting atop the diary.