Teen Pop is essentially dance-pop, pop, and urban ballads that are marketed to teens. Often, it's performed by teens, as well. Of course, music made for teenagers has been around since the dawn of the modern recording industry, from the bobby-socked girls that swooned for Sinatra to the legions of fans of Fabian or the Bay City Rollers, but teen pop is the teen music made during the late '80s and '90s. It had its first great flourish in the last years of the decade, as Tiffany, Debbie Gibson, and New Kids on the Block rode to stardom on their lite, catchy, commercial dance-pop tunes and adult contemporary ballads. NKOTB, in particular, set the template for the genre, as they name-dropped hip urban trends while remaining completely wholesome and cutely commercial. During the first two years of the '90s, teen pop dominated American charts, but once Nirvana crossed over into the mainstream, it was done for. At least, that's how it appeared. In reality, it went underground and across the sea, where Take That ruled the U.K. charts with records that were equal parts NKOTB and George Michael. They had a few peers that remained British sensations, but Take That were the undisputed kings of teen pop. Just as they were on the brink of American success with their 1994 single "Back for Good, " they imploded, just as British teens became fascinated with Brit-pop, the U.K. equivalent of the grunge revolution. For a brief time, there was no teen pop on either side of the Atlantic, but that all changed once the Spice Girls released their debut single, "Wannabe" in the summer of 1996. A photogenic, cleverly-marketed five-piece, the Spice Girls were sensations throughout the U.K., and spread like wildfire in the U.S. in 1997. Their success opened the doors for a wave of teen pop that was stronger than that in the late '80s. Hanson was the first out of the gate in 1997 with their spruced-up oldies rock, and then the Backstreet Boys eclipsed all of their peers during 1998 with a string of hit singles. Others followed in their shadow...
'Pop' means popular, but it's also a genre.
It's true that 'pop' music is whatever is popular in the literal sense, but as it's used in contemporary music criticism, 'pop' usually refers to music that follows in the tradition of the Beatles - very melodic, prominent vocal harmonies, three minutes or under, very short or nonexistent solos.
'Power Pop' is a descendent of this and is usually said to begin with Big Star, Badfinger, and The Raspberries. There are many bands playing Power Pop today such as Matthew Sweet, The Posies, Teenage Fanclub, Fountains of Wayne, Weezer, and many more.