An increasingly popular genre of Science Fiction. The term is largely self explanatory in that a space opera is a drama that is simply put in the context of science fiction. Although it can be "hard" science fiction, space operas typically focus on the characters to a point where the actual setting (space obviously, but more specifically, a technological future) is largely unimportant.

When you eat dirt for the first time and leave your family to build a shack in the woods

Generally speaking, refers to an epic adventure in space that focuses less on the technical details and more on good vs. evil and action. The mechanics of how things work ('hyperspace', 'the force') tend to be glossed over, as opposed to traditional "hard sci-fi", like Poul Anderson's "Tau Zero", where realism is emphasized, generally leading to stories smaller in scope.

Not an absolute term - Star Wars is more space opera than Star Trek, which itself is more space operaish than Deep Impact

A space opera is a grand epic drama or adventure set in a distant sci-fi future. What precisely fits into this genre is notoriously difficult to define, as it appears to encompass everything from Star Trek to the Culture universe.

A cool science fiction that generally takes place in outer space. Generally, space opera places more emphasis on the characters, the plot and the adventures rather than on the technology. The space adventures are also normally romanticized, melodramatic, "swash-buckling" and epic.

Examples of space opera:

-The "Green Lantern" comics by Geoff Johns (before his writing turned into crap)

-Jim Starlin's tales involving Thanos and Adam Warlock for Marvel Comics

-Jeff Lemire's "Trilium" series for Vertigo comics

-Rick Remender's "Fear Agent" series

-Various Image Comics series such as "Descender", "Saga", and others

-Star Wars

-Star Trek

-The anime Cowboy Bebop

-The anime Heroic Age

a.
Boring science fiction that puts the classic hero storyline in space.

b.
A musical genre that blends sci-fi, horror and fantasy with electronic music.

c.
Holy Scientologist scripture.