Is The Help a Fiction Book or Nonfiction?

The novel The Help by Kathryn Stockett which is about African American maids working in white households in Jackson, Mississippi during the early 1960s. Baring in mind the actual situation the novel is based on, it's not so clear whether it is fiction or non-fiction piece of writing.
I watched the movie and I want to know if it's based on a true story or if it's just from a book. Is it fiction or nonfiction?

The Help is a wonderful movie based on a book, not sure if it's actually a true story though.
The national director of the Association of Black Women Historians stated that in spite of efforts to market the book and the film as a progressive story of triumph over racial injustice, The Help distorts, ignores, and trivializes the experiences of black domestic workers like in the case of the three women who star the story. Moreover, the group of scholars accused both the book and the film of insensitive portrayals of African-American vernacular.