Here's a little glossary of terms used in today's Alternative Rock.

• Adult Alternative
  Adult Alternative was born in the mid-1990s, when the Alternative Rock and Grunge styles were the most popular rock styles. New artists appears, influenced by alternative bands, that were targeting the adult audiences with a music that was not too loud, nor threatening.
  (Counting crows, Cake, Tori amos, Alanis morisette, Matchbox twenty, Aimee mann).
• Alternative Country
  Music inspired by traditional Country but with a rock vision and sometimes louder guitars.
  (Cowboy junkies, Giant sound, Uncle tupelo).
• Alternative Metal
  Uses the same conventions that Heavy Metal always has - loud guitars and bludgeoning riffs - but with some post-punk concepts and without the endless guitar solos and hoarse vocals.
  (Soundgarden, Marylin manson, Henry rollins, Korn).
• Ambient Pop
  Combines conventional pop with electronic textures and atmospheres. An extension of Dream Pop that uses more electronic sound including sampling.
  (Air, Violet indiana, Stereolab, Laika).
• Brit Pop
  English pop bands with a "rock" star attitude and image, and most of the time with a Beatles like sound.
  (Oasis, Blur, Pulp, Coldplay, Travis, The verve, Supergrass).
• Chamber Pop
  Carefully orchestrated music with instruments not commonly used in rock music.
  (Nick cave, Tindersticks, Rufus wainwright, The divine comedy).
• College Rock
  Any Alternative bands that are played on the college radios.
• Digital Hardcore
  Aggressive Hardcore Punk music made digitally.
  (Atari teenage riot, Prodigy)
• Dream Pop
  Atmospheric subgenre of alternative rock that relies on sonic textures as much as melody. It often features breathy vocals and processed, echo-laden guitars and synthesizers.
  (Cocteau twins, The sundays, Luna, Echo & the bunnymen).
• Electro Industrial
  Artists that relies more on the experimental and electronic edge of industrial music than the guitar saturated and gothic image of industrial crossever bands.
  (Front line assembly, Front 242)
• Electronic Punk
  Bands that play fast-paced punk music with synthesizers and computers.
  (Shampoo, Chicks on speed)
• Emo
  Extension of Punk Hardcore, a brand of visceral yet complex guitar music driven by pendulum-esque dynamics and often deeply personal lyrics.
  (Fugazi, Braid).
• Goth
  Goth Rock had grand, baroque arrangements performed with gloomy synthesizers and processed guitars. Lyrically, Goth was dark, featuring a lot of cryptic, morbid poetry. Almost as remarkable as its sound was Goth's image: the bands and the fans usually dressed in black
  (Cure, Sisters of mercy, Christian death).
• Grunge
  A hybrid of Heavy Metal (guitars sound) and Punk (lyrics, attitude) made popular by Nirvana.
  (Nirvana, Pearl jam, L7, Hole, Stone temple pilots).
• Indie Folk
  Folk music associated with a more experimental songwriting than the average Folk artist and a more crude sound.
  (Cat power, Elliot smith, Beth orton, Ida, Indigo girls).
• Indie Garage
  Garage Rock (raw form of rock & roll) revival.
  (Boss hog, The donnas).
• Indie Pop
  General term that refers to alternative pop bands that embraces the basic tenets of Pop songwriting but filters them through the warped sensibilities of Indie Rock.
  (The high llamas, Ben folds five, Drugstore)
• Indie Rock
  General term that refers to alternative rock bands that refuses to become mainstream after Nirvana's success, they chose to stay in independent labels. Not all of the music sounds the same, but nearly every indie rock band is based in post-punk guitar rock.
  (Pavement, Jesus lizard, Throwing muses).
• Industrial Metal
  While pure industrial takes its primary cues from experimental music and electronic dance, Industrial Metal makes the distorted noise of electric guitars a crucial part of the music. It's a crossover genre between Heavy Metal and Industrial dance music.
  (Ministry, White zombie, Nine inch nails, Marylin manson)
• Lo Fi
  Lo Fi is recorded on a cheap equipment. The goal is to maintain a rough, immediate sound at the opposite of over-produced recordings.
  (Ben lee, Sebadoh, Guided by voices, The folk implosion).
• Math Rock
  Math Rock is a relation to Post-Rock, a better known indie-rock style that shares similar aesthetics. Where Post-Rock has distinct jazz influences, Math Rock is the opposite side of the same coin: it's dense and complex, filled with difficult time signatures and intertwining phrases. 
  (Chavez, Polvo)
• Neo Glam
  A revival of the 70's Glam Rock, it combines 70's Heavy Metal sound with melodic pop music with attitude.
  (Placebo, Suede)
• New Psychedelia
  Inspired by the 60s bands, with the joyful approach to making music, an eschewal of cynicism and irony, and a love for bizarre instruments as common denominator.
  (The apples in stereo, Beulah, Dressy bessy, Elf power, Of montreal).
• Noise Pop
  Pop music wrapped in noisy and distordant guitar, a mix of melodic pop songs and out of control guitars.
  (Lush, Jesus & mary chain, Ride)
• Noise Rock
  Chaotic sounds orchestrated into discordant anti-songs.
  (Sonic youth, Yo la tengo, Dinosaur jr).
• Post Punk
  Early 80's music that have roots in the independent and counterculture spirit of punk but that was interested in exploring new territories. It's the father of 90's Alternative Pop/Rock. This includes different style of music, from New Wave (Cure, Joy Division, U2) to Punk Hardcore.
• Post Rock
  Experimental form of Rock mixing Noise, Free Jazz and Electronica.
  (Tortoise, Mogwai, Aphex twin).
• Punk Folk
  See Urban Folk.
• Punk Hardcore
  The most rigid and extreme variation of punk rock. Emerging in the early '80s, it was fast paced with shouted vocals and a crude sound. Most of the bands with time, left the sound of hardcore behind, but not its ideals.
  (Beastie boys, Bad religion, Bad brains, Husker Dü, Dead kennedys).
• Punk Pop
  A post-grunge strand of alternative rock that combines power-pop melodies and chord changes with speedy punk tempos and loud guitars.
  ( Weezer, Ash, Lemonheads, Pixies).
• Punk Revival
  Emerging in the 90's Punk Revival bands were all traditionalists, keeping alive the sounds and styles of 77's Punk groups but with a heavier sound (signs of the time).
  (Offspring, Green Day, Blink 182).
• Queercore
  Punk subgenre that differs by its lyrics, which explore openly themes of prejudice, oppression, and same-sex attraction.
  (Team dresch, Butchies).
• Rap Metal
  Fusion of the most aggressive elements of Hip-Hop and Heavy Metal.
  (Rage against the machine, Limb bizkit, Kid Rock    )
• Riot Grrrl
  Subgenre of Indie Rock and Punk Rock that is distinguished by its radical feminist lyrics and its raw, willfully amateurish musical attack.
  (Bratmobile, Sleater-kinney, Le tigre, Bikini kill).
• Sadcore
  Primarily an extension of Independent Rock, Sadcore is slow, fragile and gut-wrenching music made by and for the depressed. Themes of heartbreak, loss, and misery dominate the lyrics, and the music itself is resolutely downbeat.
  (American music club, Red house painters).
• SkatePunk
  Not so different musically from Punk Revival, it's difference lies in the cultural background, it's the rock music of skateboarders.
  (NoFX, Milencolin, Labwagon).
• Slowcore
  Soft melodies shrouded in thick, dark atmospheres. Similar to Sadcore, Slowcore's concerns are far more musical than lyrical.
  (Low, Galaxie 500)
• Space Rock
  Hypnotic music defined by washes of heavily reverbed guitar, minimalist drumming, and gentle, languid vocals.
  (Spaceman 3, Mogwai, Spiritualized, My bloody valentine, Radiohead).
• Trip Hop
  Hybrid of Dance-based listening music, Jazz, Funk, and Soul.
  (Bjork, Portishead, Massive attack, Tricky, Moby, Fatboy slim, Propellerheads, Cibo matto).
• Twee Pop
  A Bubblegum Indie Rock: spirit of Punk with a simplicity and innocence not seen since the earliest days of Rock & Roll.
  (Belle & sebastian, Shonen knife, The cardigans, The softies).
• Urban Folk
  A movement of singer/songwriters that grew out of punk rock.They performed solos with an acoustic or electric guitar singing often angry lyrics.
  (Ani di franco, Michelle shocked, Vic chesnutt, Billy bragg).