Articulating his approach to screenwriting, Whedon has noted outlining and act structure as the hardest parts of storytelling, but emphasizes that he feels they are "completely essential". Many of Whedon's altered phrases and heavily popularized words have entered a common usage called "Slayer Slang", which PBS included an entire section of in their article series "Do You Speak American?". In an issue of "Buffy the Vampire Slayer Season Eight", where Buffy travels to the future, Whedon writes Buffy's reaction to the future dialect of Manhattan; this allows Whedon to comment on the series' distinctive style of dialogue; "Buffy blames herself for what's happened to the English language, and there's a lot of hubris in that joke. I like to think that adding Y's to words that don't usually have Y's is going to destroy the whole fabric of our society". His use of self-aware dialogue to humanize characters, which relies heavily on dry humor and subtext, treating clichés subversively, using misogyny to define the trait of a villain, and the recurring theme of self-sacrifice led by subverting moral icons have been defining to his style of storytelling.