An urban legend is an apocryphal, secondhand story, alleged to be true and just plausible enough to be believed, about some horrific, embarrassing, ironic, or exasperating series of events that supposedly happened to a real person. As in the "classic" examples listed below, it's likely to be framed as a cautionary tale.

Here are some classic urban legends:

• The Microwaved Pet

• The Choking Doberman

• The Boyfriend's Death

• The Hook-Man

• Humans Can Lick, Too

• The Killer in the Backseat

The phrase "urban legend" entered the popular lexicon in the early 1980s with the publication of folklorist Jan Harold Brunvand's first book on the subject, The Vanishing Hitchhiker: American Urban Legends and Their Meanings (W.W. Norton, 1981).

Legends spread from person to person

Urban legends are a type of folklore, defined as the handed-down beliefs, stories, songs, and customs of ordinary people ("the folk"). One way to differentiate urban legends from other narrative forms (for example, popular fiction, TV dramas, and even news stories) is to compare where they come from and how they're propagated. Unlike novels and short stories, which are produced by individual authors and formally published, for example, urban legends emerge spontaneously, spread "virally" from person to person, and are rarely traceable to a single point of origin. Urban legends tend to change over time with repetition and embellishment. There can be as many variants as there are tellers of the tale.

They're usually false, but not always

Though it's become synonymous in common parlance with "false belief," academic folklorists reserve the term "urban legend" (aka "contemporary legend") for a subtler and more complex phenomenon, namely the emergence and propagation of folk narratives — viral stories that are indeed usually false but which may also, on occasion, turn out to be true, or at least loosely based on real events. The crucial factor is that the story is told as true in the absence of verification. Folklorists are generally more interested in the social context and meaning of urban legends than their truth value.

Factual or not, when an urban legend is told it's meant to be believed. The teller is apt to rely on skillful storytelling and/or reference to putatively trustworthy sources — e.g., "it really happened to my hairdresser's brother's best friend" — in lieu of actual proof or evidence. Other stories rely on irrational fears, such as scary things that are unlikely to happen.

List of common characteristics

Accordingly, your typical urban legend will exhibit most or all of the following characteristics:

It's a narrative (a story).

It's of spontaneous (or indeterminate) origin.

It's likely to take the form of a cautionary tale.

It's alleged to be true though its veracity is unproven.

It's marginally plausible.

It's likely to be attributed to a putatively trustworthy secondhand source (e.g., "a friend of a friend," "my boss's wife," "my sister's accountant," etc.).

It circulates by being passed from individual to individual, orally or in writing.

It varies in the telling.

Further reading:

• How to Spot an Urban Legend

• What Is a Rumor?