Buffy the Vampire Slayer is an American television series which aired on the WB Network (and later the UPN network) from 1997 to 2003. The series spanned seven seasons and a total of 145 episodes, with an average of 22 episodes per season. The show was created by director/writer Joss Whedon and was loosely based on the Buffy the Vampire Slayer feature film starring Kristy Swanson. The show was produced by Whedon's Mutant Enemy production company as well as 20th Century Fox Television. Buffy the Vampire Slayer was a horror/comedy that centered around the titular hero Buffy Anne Summers, a high school student who also has the misfortune of being the Chosen One, the Slayer - "one girl in all the world... born with the strength and skill to fight the vampires, to stop the spread of their evil and the swell of their numbers".
Buffy Summers is the Chosen One - the Slayer. Relocating to Sunnydale from Los Angeles, she continues her ongoing battle against the vampires at Sunnydale High School which sits atop a Hellmouth. She befriends fellow students Xander Harris, Willow Rosenberg and Cordelia Chase while also entering into an intimate relationship with a vampire named Angel.
Rupert Giles is a Watcher who worked as a librarian at Sunnydale High School and later took over ownership of a magic shop. He devotes his time training Buffy (and later, Buffy's replacement slayer, Faith) in how to fight up against the vampires and the other forces of darkness that have been loosed upon the world.
Xander Harris is the good-hearted, yet nerdy friend of Buffy Summers who, although lacking in any supernatural powers or applicable skills, devotes himself towards aiding Buffy in her fight against the forces of evil. After a spell temporarily bequeathed him military combat skills, Xander became a more effective ally and managed to retain some of his combat skills even after the effect wore off.
Willow Rosenberg was a nerdy high school student and the best friend of Buffy Summers. She began practicing witchcraft and became an invaluable part of the Scoobies. She dated a werewolf named Daniel Osbourne and later turned towards homosexuality, entering into a relationship with a girl named Tara Maclay. Willow briefly turned evil, but returned to normal with the help of her friend Xander Harris.
Cordelia Chase was the "popular" girl at Sunndyale High. A respected member of the high school cheerleading team, she and her followers, the Cordettes, made sure that the unpopular kids knew their place. Cordelia became a foil to new student Buffy Summers and eventually learned that Buffy was the Slayer. Although the two never became close, they settled many of their differences following the Homecoming dance.
Angel was a tormented vampire cursed with a soul. As such, he was forced to endure the unmeasurable guilt of his past crimes. Seeking to atone, he aids Buffy in her battle against evil and the two eventually fall in love. Angel is corrupted by his darker side however and wreaks untold havoc against Buffy and her peers. He eventually recovers from this and goes on to become a dark warrior seeking redemption.
Oz is an introverted musician who also happens to be a werewolf. He begins dating Willow Rosenberg and becomes a member of the Scooby Gang. When a group called the Initiative learn about Oz's lycanthropy, he is taken prisoner by them and experimented upon.