"It" is a horror novel by Stephen King, published in 1986. The story takes place in the fictional town of Derry, Maine, and follows a group of childhood friends, known as the Losers' Club, as they face their deepest fears and confront a malevolent entity that preys on the town's children.

The novel is split between two time periods, the 1950s and the 1980s. In the 1950s, the Losers' Club consists of Bill, Ben, Beverly, Richie, Eddie, Mike, and Stan. They discover that a malevolent entity, which they call "It," is responsible for the town's string of child murders and other horrifying events. The entity can shapeshift into any form, but often appears as Pennywise the Dancing Clown. The Losers' Club bands together to fight It, eventually forcing It into hibernation for 27 years.

In the 1980s, the Losers' Club has grown up and moved away from Derry, but they are called back to fulfill a promise they made to each other as children. They must face It once again, and as they delve deeper into the mystery, they realize that their childhood memories may hold the key to defeating the monster once and for all.

Throughout the novel, King explores themes of trauma, memory, and the power of friendship. The Losers' Club must confront their own traumas and fears in order to defeat It, and the novel shows how the events of childhood can shape a person's entire life.

"It" has been adapted into several media, including a 1990 TV miniseries and a 2017 film. The novel is considered a classic of the horror genre and is often cited as one of King's greatest works. Its popularity has also spawned a cultural phenomenon surrounding Pennywise the Clown, who has become an iconic figure in popular culture.

Overall, "It" is a haunting and suspenseful novel that explores the power of fear and the strength of human connection. King's masterful storytelling keeps readers on the edge of their seats, and the novel's themes continue to resonate with readers today.