What is Shingeki no Kyojin?

Attack on Titan (進撃の巨人 Shingeki no Kyojin?, lit. "Advancing Giants") is a Japanese manga series written and illustrated by Hajime Isayama. The series began serialization in Kodansha's Bessatsu Shōnen Magazine magazine from September, 2009 and is published in North America by Kodansha Comics USA. A spin-off light novel began release from December 2011 and has also received a manga adaptation.