Essential Albums of the Decade: 21 to 40

21. Rilo Kiley - Under the Blacklight (2007). With hints of country and Fleetwood Mac, Rilo Kiley's fourth album was its best and most accessible, with lovely melodic songs like "Silver Lining" and the title track, as well as a little rock swagger on "The Moneymaker" and "Close Call." Best: Under the Blacklight.

22. Black Kids - Partie Traumatic (2008). Black Kids' synth-driven indie pop was one of the best alternative music debuts of the decade. It's upbeat atmosphere gives way to the lyrical longing of songs like "Hurricane Jane" and "I'm Not Going to Teach Your Boyfriend How to Dance." Best: Hurricane Jane.

23. Coldplay - X&Y (2005). A Rush of Blood to the Head was a hard act to top, and Coldplay didn't quite rise to the challenge on their third album. That said, it's still quite a beautiful work, darker and broader in scope than either of their first two sets, with heavier reliance on synthesizers and studio effects to round out its dramatic productions that strive for U2-like grandeur. Best: Talk.

24. Coldplay - Viva La Vida or Death and All His Friends (2008). Best: Strawberry Swing. That Coldplay turned to longtime U2 producer Brian Eno to helm their fourth album was further proof that the band's music was veering in that great Irish band's direction. While that seems like an obvious play, Viva La Vida holds more than its share of surprises, like the multi-part "42," strings-based rocker "Viva La Vida" and sumptuous "Strawberry Swing." Best: Strawberry Swing.

25. Madonna - Confessions on a Dancefloor (2005). Following the less than impressive results of American Life, Madonna teamed up with British dance producer Stuart Price, and made this--her first dance pop album since Erotica. Seamlessly mixed together like one continuous night of clubbing, Confessions reaffirmed Madonna's status as the greatest dance pop artist of all time. Best: Get Together.

26. Madonna - Hard Candy (2008). Despite being a major success in Europe, Confessions on a Dancefloor did not connect with Americans, who spent most of the 2000s listening to pop music with hip-hop and alternative flavors but little in the way of dance pop until Lady GaGa hit the scene. Always determined to have a hit, Madonna embraced the R&B-pop sound with this album, co-produced with Timbaland, Danja and the Neptunes. Despite some fan objections, it was still a Madonna album through and through. Best: Miles Away.

27. Air - Talkie Walkie (2004). French techno duo Air's fourth album featured otherwordly electronic compositions that also prominently featured acoustic instruments. The album is generally pretty mellow, save for '80s-esque synth-fueled "Surfing on a Rocket." Best: Surfing on a Rocket.

28. Dido - No Angel (2001). Dido's debut, No Angel, released in 1999 in the US but not until 2001 in the UK, could have sounded like any other female singer-songwriter work of the time if it wasn't for the appealingly dark downbeat production courtesy of Dido's brother and Faithless member Rollo Armstrong. Best: Here With Me.

29. Alexandra Burke - Overcome (2009). Exuding warmth, personality and versatility on Overcome, The X Factor's fifth winner, Alexandra Burke, made the best album to come from any of the show's famous alumni, effectively tackling big ballads ("Overcome"), frothy dance pop ("Broken Heels") and old school soul ("Six Feet Under"). Best: Bad Boys.

30. Goldfrapp - Supernature (2005). Goldfrapp's third album delivered much the same style of music as their second--slinky, mostly uptempo electro-pop--but with an eye for greater mainstream success, which they achieved with top 10 hits like "Ooh La La" and "Number 1." Best: Satin Chic.

31. Coldplay - Parachutes (2000). Coldplay became a major breakout in 2000 on the back of their debut album, a melodic set of relatively simple but well crafted guitar rock songs. It was a smash hit, especially in Britain, where it won the Brit Award for British Best Album (and award every Coldplay album but Viva la Vida has won). Looking back, perhaps the most interesting thing about this album was that it was the least interesting they would ever be. Best: Trouble.

32. Green Day - American Idiot (2004). Once just another goofy punk band, on American Idiot the punks matured into respectable rock musicians, delivering a politically charged concept album that explored the struggle of the common person in post-9/11 America--while winning much acclaim and popularity in the process. Best: Wake Me Up When September Ends.

33. The Killers - Hot Fuss (2004). New wave revival was one of the decade's biggest trends in alternative rock, and this was one of the first albums to bring the sound to a mainstream audience. The Killers scored big on their debut, with charging rockers set to '80s synth-driven melodies. Best: All These Things that I've Done.

34. Little Boots - Hands (2009). Little Boots made shimmery, '80s-style electro-pop on her debut, transforming herself from a quirky club act (where she liked to perform on stage with a Japanese gizmo resembling an '80s electronic toy) to a bona fide pop star. Best: Stuck on Repeat.

35. Kylie Minogue - Light Years (2000). After two less than stellar albums on the Deconstruction label, during which Kylie explored a new sound, she returned to making glittery dance pop, updating her sound for the disco-revival era with this campy, thoroughly joyous album. Best: Loveboat.

36. Beyonce - I Am...Sasha Fierce (2008). After two promising but flawed albums, Beyonce finally delivered the hit album we always knew she could make. Split into two, I Am...Sasha Fierce demonstrated Beyonce's continually improving vocal prowess over its gentle first disc as well as her immense talent as an uptempo performer on the edgier second disc. Best: Single Ladies (Put a Ring on It).

37. The XX - XX (2009). Like a chill-out version of The White Stripes, London-based XX's debut album employed a minimalist approach to its finely crafted guitar-based melodies set amidst a late-night hush of plucked guitar, keyboard effects and contrasting male and female lead vocals. Best: Infinity.

38. Rachel Stevens - Come and Get It (2005). That Rachel Stevens didn't break out as a major star on the back of this pulsing dance pop album was one of the great pop music travesties of the decade. Trust me, this shiny dance pop album was more than just a stopgap between Kylie discs. Best: Secret Garden.

39. Will Young - Friday's Child (2003). Before Kelly Clarkson, Carrie Underwood, Girls Aloud, Leona Lewis and Joe McElderry there was Will Young, winner of the first season of Pop Idol and the first winner of a reality TV singing competition to really go on and make a music career in his own right. On this, his second album, he showed that artists with such a start can move past their TV beginnings into true pop musicians. Best: Leave Right Now.

40. Hard Fi - Once Upon a Time in the West (2007). Bolder and grander than their 2005 debut, Hard-Fi's second album shows the band embodying a more mainstream British rock sound. Best: Tonight.