If you haven't read the books, chances are you've heard of the film adaptations, which feature a cast young actors with a fanatic following.
Twilight, the first movie, has grossed more than $380 million worldwide since its November 2008 release. The second installment, The Twilight Saga: New Moon, also shattered box office records.
Even if you're not a Twi-hard or a Twi-mom (think "devoted fan"), you can still enjoy the other films in the series—Eclipse and Breaking Dawn—with a little Vampire 101. Here's what you need to know.
It all begins when Bella Swan, a teenager with a propensity for clumsiness, moves from Phoenix, Arizona, to Forks, Washington, a sleepy town that has more rain and snow than sunshine. Bella moves in with her father, Charlie, the local chief of police, so her mother can travel freely with her new husband, a minor league baseball player.
On her first day at Forks High School, Bella's world changes forever when she meets Edward Cullen, the mysterious boy seated next to her in biology class. According to Bella's other classmates, Edward and his adopted siblings, Alice, Jasper, Emmett and Rosalie, are the most beautiful students at school—with the best cars—but they stick to themselves.
Their immediate connection is undeniable, and after Edward uses his bare hands to shield Bella from a speeding van, she sets out to discover his secrets.
Edward refuses to answer her questions, so Bella turns to an old family friend, Jacob Black, for information. Jacob is a member of the Quileute tribe in nearby La Push, where he lives on a Native American reservation with his father, Billy.
During a day at the beach, Jacob lets his guard down and tells Bella a tribal legend about the battle between his people and creatures known as "the cold ones." We know them as vampires.
Read the Quileute legend in this excerpt from Twilight.
After a little Googling, Bella concludes that, in regards to Edward, all signs point to vampire. But it's too late. She's already fallen deeply in love with him and refuses to stay away...even after he admits that the scent of her blood is almost too tempting to resist.
Some vampires also have special gifts. Edward can read minds, but for an unknown reason, he can't see what Bella is thinking. Alice, his sister, can predict the future.
Just as Bella is getting to know Edward's vampire family, another coven rolls through Forks. Unfortunately for Bella, these vampires are only interested in one kind of animal—human. James, the coven leader and a tracker, sets his sights on Bella.
James and his mate, a striking redhead named Victoria, hunt Bella from Forks to Phoenix. There, he lures her to a ballet studio and manages to get a bite in before the Cullens arrive.
Edward sucks the venom from Bella's blood, saving her from becoming a vampire. James isn't so lucky. The Cullens rip him from limb to limb before burning his body—the only way to kill a vampire. Victoria escapes.
After being released from the hospital, Bella and Edward return to Forks in time for her junior prom. While dancing under the stars, Bella tells Edward she wants to become a vampire and join his coven, but he refuses.
The second book in Stephenie Meyer's four-part series begins on Bella's 18th birthday. Edward invites her to his home to celebrate with his coven, and Alice goes all out to commemorate the occasion. Decorations, gifts and a birthday cake set the scene, but in a flash, all is ruined. When Bella gets a paper cut while opening a present, the smell of blood sends Jasper, the most recent vampire to join their coven, into a frenzy. Jasper lunges for Bella, but Edward pushes her aside and saves her life.
After saving Bella from another near-death experience, Edward makes the heart-wrenching decision to break up with her and leave Forks. Though his intention is to protect Bella from harm, Edward only succeeds in breaking her heart. For months, Bella falls into a deep depression. She pulls away from her father and her classmates and rarely leaves her bedroom.
Over time, Bella finds comfort in the company of her old friend Jacob. Together they set out to repair two old motorcycles, and during this time, Jacob also helps piece Bella's heart back together.
Then, after Jacob visits Bella one night, she figures out his secret. Jacob is a werewolf. She learns that Jacob and a few other young men in the Quileute tribe can "phase" into shape-shifting creatures that are intended to hunt vampires and protect people from evil bloodsuckers. The wolf gene is genetic, passed down through the Quileute bloodline to select men and women.
When Victoria, a bloodthirsty vampire out to avenge her mate James' death, sets her sights on Bella, Jacob and his wolf pack vow to protect her.
Then, after Bella jumps off a cliff and nearly drowns, Alice returns to Forks because she thinks her dear friend has died. When Alice sees that Bella is alive, she's relieved, but their reunion is cut short by disturbing news.
To stop Edward from doing something drastic, Alice and Bella fly halfway around the world and race through Volterra's crowded streets. Bella reaches Edward seconds before he breaks a long-standing vampire rule. If he had broken this rule, the Volturi would have sentenced him to death.
Edward and Bella share an intimate moment before being whisked inside the Volturi's castle alongside Alice. The three leaders—Aro, Caius and Marcus—are intrigued by Bella and Edward's love for her. Aro asks Alice, Edward and Bella to join the Volturi, but they refuse.
Then, the Volturi pass down a verdict. Edward must change Bella into a vampire soon, or they will kill her.
After returning from Italy, Edward reveals that he can't live in a world without Bella and promises to stay by her side forever. Their love is restored, but Edward still refuses to change Bella into a vampire...unless she agrees to marry him.
As the second installment comes to an end, Victoria is still on the loose, hunting Bella and posing a danger to all humans living near Forks. And despite Edward's gratitude for his actions, Jacob, a mortal enemy of vampires, promises retribution if Edward ever turns Bella into a vampire.
More from our Twilight character guide
The series' narrator is a fair-skinned brunette who moves in with her father, the chief of police in Forks, Washington, during her junior year of high school. Bella is described as clumsy and stubborn, and she faints at the sight of blood. Despite her male classmates' best efforts, she only has eyes for one boy, Edward Cullen.
(played by Robert Pattinson)
As a vampire, Edward is impossibly beautiful, strong and fast, but he wasn't always this way. Edward was born in 1901, and at age 17, he contracted Spanish influenza. As he lay on his deathbed, Dr. Carlisle Cullen transformed him into a vampire to prevent him from dying.
Dr. Cullen teaches Edward to live as a "vegetarian" vampire, which means drinking the blood of animals instead of humans. Over time, Edward develops a taste for mountain lion. Edward doesn't sleep or eat human food, but he can read minds and play the piano.
(played by Taylor Lautner)
Bella has known Jacob, the son of her father's close friend, since she was a child. Jacob is a member of the Quileute tribe and lives on a Native American reservation in La Push, Washington. Though Jacob is two years younger than Bella, he's tall for his age and is described as having russet skin, black hair and dark eyes. Jacob has a crush on Bella, which leads him to reveal tribal secrets to her.
Dr. Carlisle Cullen
(played by Peter Facinelli)
Edward's adoptive father may look young, but he was born in 1640. After becoming a vampire, he learned to survive without killing humans and grew accustomed to the smell of blood. Over the years, he's transformed four people into vampires—Edward, his wife, Esme (pictured left), and two other adopted children, Rosalie and Emmett. Dr. Cullen is also responsible for forging a treaty with Quileute leaders that allows the coven to live near the tribe if they promise not to kill a human or trespass on their land.
Alice, Jasper, Rosalie
and Emmett Cullen
Carlisle and Esme act as parents to Edward and his four adoptive siblings, Alice, Jasper, Rosalie and Emmett. Alice, a pixie-like vampire, has the special ability to see the future. She quickly becomes Bella's close friend and even orchestrates her prom-night makeover. Jasper, the newest vampire in the coven, is Alice's mate and is known for his ability to read and control emotions. Rosalie, a stunning blonde with a chip on her shoulder, and Emmett, a vampire known for his strength, are also a couple.
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