When you think of music moments of the past decade, few moments come close to Adele's 21. At the peak of the 21 era, your day could go like this: "Rolling in the Deep" in the car, "Someone Like You" in the grocery store, "Turning Tables" in a department store, "Rumor Has It" in a television show, and "Set Fire to the Rain," on the car ride back. 21 dominated the world, but the word "dominated" feels too light for how pivotal the album was. For younger millennials and Gen Z, Adele's 21 was the closest thing in commercial impact to Michael Jackson's Thriller. As of January 2020, 21 has sold a little over 12 million copies in the United States; it is the best-selling album of the 2010s decade. The only album to come close to that number happens to be Adele's own 25 which is also the only album in the past decade to sell over 9 million copies. The 2010s were a decade that saw the shift from pure digital sales to streaming. CD sales dropped, vinyl saw a relative resurgence, and digital sales continued to fall. Nonetheless, streaming grew exponentially and became the dominant form of music consumption this decade. Somehow, 21, and later 25, defied the odds and pulled out pure sales numbers that seemed unimaginable. There are currently 123 albums that have achieved a Diamond (10,000,000 copies sold) certification from the RIAA. Only two of those albums were released in the 2010s — 21 and 25. As the longest-charting album by a female artist on the Billboard 200 and the best-selling album of the 2010s globally as per the IFPI, "monster" doesn't even begin to describe 21. In addition to its tens of millions of albums sold, 21 spawned 3 #1 singles on the Billboard Hot 100, won 6 Grammys (including Album, Record, and Song of the Year), and was ranked the Greatest Billboard 200 album of all time for its chart performance.

21 is more than the numbers. At its core, the album's sincerity and its eclectic mixture of influences and collaborators drove its success. 21 was so huge because it achieved the rare feat of being an album that was accessible to virtually everyone and every taste without sounding incohesive or bland. Like any proper lead single should, "Rolling in the Deep" set the tone for the entire album. Anchored by menacing guitar licks, militant stomps and drums, and bluesy background vocals, "Rolling in the Deep" continuously builds into a towering anthem that revels in hurt and longing with a splash of vindictiveness. It's the kind of song that feels unique but could theoretically work on any radio format. And it did. "Rolling in the Deep" charted on Billboard's radio airplay charts for the Pop, Alternative, Latin Pop, Adult Top 40, Rock, Mainstream Top 40, Adult Contemporary, and Rhythmic formats. The best-selling digital single of all time, "Rolling in the Deep" had the kind of cross-cultural, cross-genre, and cross-generational appeal that few songs ever achieve. Regardless of your personal music preferences or age, you could find something in the song to connect with. A monster lead single like that was only going to lead to an even bigger album. The sprawling appeal of 21 was, and continues to be, its superpower. At its core, 21 is a pop album, but Adele weaves a plethora of different genre influences throughout the record to create this symphonic quilt of greatness. Take the bridge of "Rolling in the Deep," for example. The stomp-clap breakdown evokes notes of gospel and roots that eventually morph into sweet blue-eyed soul by way of pounding piano keys.

Adele's voice expertly lends itself to blue-eyed soul. Her cigarette-induced rasp and cavalier vocal delivery helped translate her near-universally beloved tone across the different influences of 21. Of course, the album is mostly informed by blues and soul from the loungy "He Won't Go" to the doo-wop-inflected "Rumor Has It." It should be noted, however, that while Adele's pastiche of soul helped the album reach a broader audience, her whiteness prevents her pastiche from being anything more than surface-level because she does not have the intrinsic connection to soul music's sociopolitical roots that Black artists do. This foundation of soul, combined with deeper explorations of country and americana and the glossy Top 40 sheen of producers like Ryan Tedder, resulted in an album that had its hand in every musical pot. 21 could be embraced by everyone, but its specific iteration of this combination of influences was completely unique to Adele. The country and americana influences that inform 21 are often overlooked in favor of the album's showier moments like the robust "Set Fire to the Rain" or the instant classic "Someone Like You." Nonetheless, those influences are by far the most interesting on the entire album. There are hints of it on the intro to "Rolling in the Deep," but it's best showcased on "Don't You Remember" and most of the album's bonus tracks. On "Remember," Adele utilizes live instrumentation (primarily drums and guitar) and, lyrically, employs a more straightforward narrative approach. Some of 21's biggest hits ("Rolling in the Deep," "Set Fire to the Rain," "Turning Tables,") preferred metaphor-driven songwriting and busier production, but "Don't You Remember," one of the album's true standouts, rested on the back-to-basics energy of country and americana. While touring extensively in the American South in support of 19, her debut album, Adele was introduced to the sounds and stylings of country music greats like Wanda Jackson, Alison Krauss, Lady A (f.k.a Lady Antebellum), etc. Her tour driver, a Nashville, TN, native, also introduced her Garth Brooks, Rascal Flatts, and more. The honesty of country music songwriting is apparent throughout 21, but it's the covers included as bonus tracks that truly seals the deal. There's the immaculate "If It Hadn't Been For Live," a Steeldrivers cover written by none other than Chris Stapleton, "Hiding My Heart," a gorgeous Alison Krauss cover, and a recording of her Darius Rucker-assisted live cover of "Need You Now" at the CMT Artists of the Year awards. Not only does the heavy country influence of 21 offer a nice contrast to glossy blues-pop numbers like "Rumor Has It," but the songs also widened Adele's already incredibly broad appeal. Literally, everybody could find something to enjoy in the album.

Debuting at the beginning of 2011, 21 dominated in a year that yielded Billboard Hot 100hits like Nicki Minaj's "Super Bass," Pitbull's "Give Me Everything," LMFAO's "Party Rock Anthem," and more. Bombastic dance-pop was the name of the game, and 21 couldn't have been a stronger pivot from that sound. Between Rick Rubin's insistence on live instrumentation and Adele's already vocal-first approach to music-making, 21 could not have sounded more different from Lady Gaga's Born This Way, for example. In this way, Adele was able to connect with such a wide audience not only because of her music and her voice but also because of her image. Compared to her pop music peers, Adele's image was fairly conservative and essentially devoid of controversy. Adele, Taylor Swift, Katy Perry, Nicki Minaj, and Lady Gaga all debuted or had their mainstream breakthroughs during the same 2-3 year stretch. While most of her peers were known for outrageous stage shows, over-the-top fashion moments, various controversies, and political music and stances, Adele simply stood and sang. Adele's simple stage show simultaneously positioned her as the "great vocal talent" of her generation, evoked the traditional singer-songwriter type that seemed to be missing from the new class of pop stars, and emphasized her separation from the electronic dance-pop that dominated that era. More often than not, simply standing and singing gives the illusion that an artist is a more gifted or skilled vocalist than they actually are, and this worked in Adele's favor despite her already being a solid singer. Adele was an artist that people could listen to with their parents and with their children. Everyone could relate to the themes of lost love, alleged infidelity, deteriorating romance, etc. Also, who can resist a piano-and-vocal ballad that offers as much closure as "Someone Like You?"

21 is a phenomenal and historic record. It feels ludicrous to say that it has been ten years since the album's release, but here we are. We likely will never see an album dominate the world the way 21 did. With one record, Adele underwent a metamorphosis from blue-eyed soul prodigy to a once-in-a-lifetime global pop phenomenon. Until someone is able to arrive at the perfect storm of good music, wide appeal, and a conflicting wider musical era — there will never be another 21. And that's more than fine. Music wouldn't be interesting if every album was like 21. It is fun, however, to look back on the legacy of this gargantuan album. One could debate the immense impact a song like "Someone Like You," had on American Mainstream Top 40 radio. Would we still see such wide success of piano-and-vocal ballads like "When I Was Your Man" (Bruno Mars) or "All of Me" (John Legend) without the success of that song? Above all, it's been ten years and every single song and bonus track from 21 still holds up. It's truly timeless.