According to It, when humans got scared, "all the chemicals of fear flooded the body and salted the meat". This is why he prefers to feast on children -- their fears are simple, pure, and powerful compared to the complex, pathological fears of adults. Basically, children are delicious.
In both the book and the films, It is an ancient alien creature, older than civilization, and in King's novel, older than our universe. It feasts on the flesh of humans simply because our fears are easy to manifest and they make us taste better.
It disguises itself as many frightening things in the movie. Pennywise can morph his mouth into a giant gaping mouth with layers of sharp teeth which he uses it mangle and eat his victims.
Also in the 2017 film, Georgie's death is changed. As well as having his right arm bitten off, Georgie is trying to crawl away but he was dragged into the sewers and devoured by Pennywise, with an unnamed older woman and her cat being the sole witnesses of the horrific scene, including before Georgie lost his arm.
Bill Skarsgård as Pennywise in “It.” [Photo: Brooke Palmer, courtesy of Warner Bros. Pictures] In King's book, Georgie Denbrough apparently dies from complications due to having his arm ripped off by a reptile-toothed clown.
IT arrived on Earth through an event similar to an asteroid impact, landing in what would later become Derry, Maine. Once there, IT adopted its usual pattern of hibernation that lasted between 27 and 30 years, awakening to kill and eat and then going back to sleep.
In the novel, It claims that its true name is Robert "Bob" Gray, but decided to be named “It”. Throughout the book, It is generally referred to as male, usually appearing as Pennywise. The Losers come to believe It may be female after seeing it in the form of a monstrous giant spider that lays eggs.
Pennywise offers Georgie his boat back, but when Georgie attempts to reach out to it, Pennywise grabs Georgie's arm and bites it off, leaving Georgie to bleed to death in the rain.
In their final battle, the Losers' Club was able to kill Pennywise by reducing him to a child-like form as they overcame their fears.
This proves to be its undoing; Eddie nearly chokes it when it takes the form of a leper and is small enough for him to do that. When sufficiently weakened, the Losers kill It by crushing the heart it must have in the form of Pennywise the Dancing Clown.
Though there are some IT characters just as scary as Pennywise, the film's main villain proves to be its deadliest, with a kill count that actually reaches into the tens of thousands. Reddit user u/angelholme estimates that Pennywise actually took the lives of between 12,117 and 18,011 people.
Stephen King's IT introduced readers to a one-of-a-kind creature that can take any form, the most common one being Pennywise the Dancing Clown, and as menacing as it is, this creature has one big enemy it's truly scared of: Maturin, the turtle.
The rest of the group realizes they can defeat it by shrinking it and therefore weakening it, which they achieve by standing up to it. They take out IT's heart and proceed to crush it, finally killing it. Eddie dies and his body is left behind.
Pennywise never seems to bother offing the older folks in Derry, but he has taken out older teenagers and young adults as well as children. It's established early on that Pennywise prefers the taste of children over other types of prey, but such a diet would undoubtedly raise too many questions.
However, It must surrender the the laws of whatever shape It takes. Pennywise's strength is also his weakness. For example, if he were to take the shape of a werewolf (as he does in the novel), silver bullets would harm him.
And if his victim believes him to be powerless, he will become powerless. And so the group figures out that their best bet is, essentially, to bully the bully: They mock Pennywise, telling him he isn't scary. Humiliated, Pennywise begins to shrink, transforming into an almost Benjamin Button–like, melted clown-baby.
Kersh is Pennywise's daughter. Or at least the daughter of the man who originally had Pennywise's face. Additionally, the trailer offers a first glimpse of Bill (James McAvoy), Ben (Jay Ryan), Richie (Bill Hader), Eddie (James Ransone), and Mike (Isaiah Mustafa) back together.
Image via Warner Bros. Finally, Pennywise is beaten into submission. He scurries away, utters the word "fear," and partially disintegrates before falling into the void. It's a powerful defeat of a powerful monster, and it's satisfaction enough were IT to remain a single film.
there is no confirmation that Georgie is dead. He's attacked by Pennywise, and he's missing an arm, and he tries to get away from the sewer, like he's dragged into it again, leaving a trail of blood, but his body is never found.
A neighbor witnesses his disappearance, but the fact his body is never found gives Bill hope Georgie somehow survived. Pennywise prays on this in the film, using that hope to lure Bill in the finale. Bill later finds the tatters of Georgie's coat and finally accepts his brother is gone.
In the novel, It's origins are nebulous. He took the form of a clown most frequently, Mr. Bob Gray or Pennywise, but his true form is an ancient eldritch entity from another universe who landed in the town that would become Derry by way of an asteroid and first awoke in 1715.
In Stephen King's novel It, Maturin communicates with Bill, the leader of the Losers Club, and helps the Losers Club defeat It by lending them strength. It comes in many shapes and sizes. Most iconically, It takes the form of Pennywise the Clown, whose real name is actually Bob Gray (anticlimactic, honestly).