In a country as homogenous
as South Korea
is pretty much the only genre
of music there is. Of course, it can be broken into a few sub-genre
The regular stuff: This is pretty much like pop music in North America (eg Brittney Spears, Aqua, Ricky Martin and so forth), with the obvious difference that the lyrics are in Korean. Easy to dance to, simple, catchy tunes that stick in your head and repeat over and over, ad nauseum, until you feel your sanity begin to slip away.
Sappy love songs: Also musically similar to the North American equivalent, the main difference is in the music videos. Every one is a narrative, with the same plot: Boy sees beautiful girl. Boy approaches girl. Boy is ignored. Boy spends most of the video doing various sweet things in order to win the girl's love (in one video, for instance, the girl buys a potted plant, which she drops while crossing the street. After she's gone, the boy collects the plant and dirt, finds a new pot, puts it in, and brings it to her house). Eventually, he wins her over, at which point one of them is promptly killed in some sort of tragic accident. It seems that the Korean music industry sees tragedy as a necessary part of romance.
Boy bands: The Koreans have jumped the bandwagon in a big way when it comes to this craze. Despite their visible ethnic difference, they do their best to fit the stereotypes; usually four or five guys with boyish good looks and bleached blond hair sing a mixture of slow love songs and upbeat happy songs.
Hip hop: Not technically pop, but the Korean music industry has sucked all the creativity and originality out of this genre, effectively making it a sub-genre of pop. Perhaps the term "hip pop" should be coined, if it hasn't been already. In any case, the Koreans don't make any distinction between it and other pop sub-genres, so I include it. It's worth mentioning Korean hip hop has assimilated the North American hip hop fixation on money and women; the cover of one album, called Game, features the singer sitting in a room wall-papered with playing cards, smoking a giant cigar and holding a huge stack of dollar bills, while being waited on by scantily clad women.
Ripped-off North American tunes: Easily a quarter or a third of Korean pop songs are simply classic North American pop songs, performed by Korean bands and with new (Korean) lyrics. Off the top of my head, three songs that are incredibly popular here right now are to the tune of She Bop, Bad Case of Loving You and My Angel is a Centerfold. For most of them, the Korean lyrics don't have anything to do with the original ones; only the tune is the same.