“NOW That’s What I Call Music!,” the global franchise that compiles the biggest songs of the day, celebrates a milestone this month with the release of the 100th installment of the original U.K. series.

The American editions of the “NOW” albums once were an essential introduction to popular music — the Spotify “Today’s Top Hits” playlist of their time.

The American versions are just up to volume 67 — out Friday and featuring the likes of Ella Mai’s “Boo’d Up” and Post Malone’s “Psycho.” But that’s still 67 albums spanning 20 years of chart-topping history.

With that in mind, we offer the 14 essential “NOW“ albums.

Volume 2, 1999

Jay-Z, seen in 2017 at the Austin City Limits Music Festival, made Volume 2 with “Hard Knock Life (Ghetto Anthem).”

Jay-Z, seen in 2017 at the Austin City Limits Music Festival, made Volume 2 with “Hard Knock Life (Ghetto Anthem).” | AP

Volume 4, 2000

Even better was Volume 4, with era-defining songs such as Jennifer Lopez’s “Waiting for Tonight,” Eiffel 65’s “Blue (Da Ba Dee),” Train’s roots rock classic “Meet Virginia” and Blink-182’s defining hit “All the Small Things” alongside one of the decade’s best one-hit wonders, Macy Gray’s “I Try.”

Volume 6, 2001

Volume 6 had Britney Spears’ “Stronger,” NSYNC’s “Bye Bye Bye” and Backstreet Boys’ “Shape of My Heart,” plus rock hits that still hold up, from Coldplay’s “Yellow” to Creed’s magnum opus “With Arms Wide Open.” Bonus points for the novelty inclusion of Shaggy’s “It Wasn’t Me.”

Britney Spears, seen here performing during her "Britney 2001 Tour" in Anaheim, Calif., made Volume 6 with “"Stronger.”

Britney Spears, seen here performing during her “Britney 2001 Tour” in Anaheim, Calif., made Volume 6 with “”Stronger.” | AP

Volume 8, 2001

This had eternal single “Bootylicious” from Destiny’s Child and Usher’s “U Got It Bad,” the meandering funk of Gorillaz’s “Clint Eastwood” and Sum 41’s “Fat Lip.” Plus, from the “Shrek” soundtrack: Smash Mouth’s cover of “I’m a Believer.”

Volume 15, 2004

Britney Spears’ “Toxic” might be the best pop single of the 2000s, featured here with the likes of “It’s My Life” from No Doubt and Beyoncé’s “Me, Myself and I,” Sheryl Crow’s “The First Cut Is the Deepest” and Norah Jones’ “Sunrise,” plus relics of mid-2000s hip hop such as Ludacris’ “Stand Up” and Chingy’s “Holidae In.”

Volume 19, 2005

Bookended by two of the 2000s’ most enduring hits: Gwen Stefani’s “Hollaback Girl” and The Killers’ “Mr. Brightside.” Also features fun one-hit wonders: Amerie’s “1 Thing” and Anna Nalick’s “Breathe (2 AM).”

Volume 20, 2005

Beyond enduring dance-floor hits such as Missy Elliott’s “Lose Control” and Rihanna’s “Pon de Replay,” Kelly Clarkson was at her peak emo-wise with “Behind These Hazel Eyes,” Weezer has the lovably dumb “Beverly Hills,” and Fall Out Boy’s “Sugar, We’re Goin Down” rocketed the band to mainstream fame. Also, “Fix You” remains one of Coldplay’s best singles.

Volume 30, 2009

This album goes beyond combined heavyweight powers of “Just Dance” from Lady Gaga and Britney Spears’ “Womanizer.” “Heartless” is from Kanye West’s “808s and Heartbreak,” which dictated the next decade of hip-hop trends, and Kevin Rudolf and Lil Wayne’s bizarre country-rap collaboration “Let It Rock” could be the spiritual predecessor to Post Malone.

Volume 33, 2010

Beyond obvious pop favorites such as Kesha’s “TiK ToK” and Lady Gaga’s “Bad Romance” and the solid-gold country anthems “Need You Now” from Lady Antebellum and Taylor Swift’s “Fearless,” Volume 33 captures what a strangely hilarious year 2010 was for music, from the absurd Young Money posse cut “BedRock” and doofy ukuleles of Train’s “Hey, Soul Sister” to the bizarre phenomenon that was Owl City’s “Fireflies.”

Volume 38, 2011

Lady Gaga’s “Born This Way” kicks off this compilation of thumping pop hits from Rihanna (“S&M”), Britney Spears (“Hold It Against Me”), Usher (“More”), Kesha (“Blow”) and Katy Perry (“E.T.” featuring Kanye West). Also here are Chris Brown’s “Look at Me Now” and the iconic Adele single with a chorus that we still don’t quite know what it means, “Rolling in the Deep.”

Volume 46, 2013

“Locked Out of Heaven” and “I Knew You Were Trouble” were top-three best singles for Bruno Mars’ and Taylor Swift. Pink and Nate Ruess’ sweet “Just Give Me a Reason” still holds up, and Sky Ferreira’s “Everything is Embarrassing” is rightfully included, too.

Pink and Nate Ruess, performing at the Grammy Awards in January 2014, deservedly made Volume XX with their sweet collaboration "Just Give Me a Reason."

Pink and Nate Ruess, performing at the Grammy Awards in January 2014, deservedly made Volume 46 with their sweet collaboration “Just Give Me a Reason.” | Getty Images

Volume 60, 2016

Includes “This Is What You Came For” from Calvin Harris, featuring Rihanna, and Ariana Grande’s “Into You,” plus Charlie Puth’s best hit to date — “We Don’t Talk Anymore,” with Selena Gomez — and Hailee Steinfeld’s sneakily good “Starving.”

Volume 63, 2017

We were lucky to have “I’m the One” and “Slide” as DJ Khaled and Calvin Harris’ songs-of-the-summer contributions, “Congratulations” is Post Malone’s most essential single.

Volume 64, 2017

This had the best Maroon 5 song in recent memory — the shamefully enjoyable SZA collaboration “What Lovers Do” — plus Childish Gambino’s pitch-shifted funk on “Redbone” and the raw power of Kesha’s “Praying.” Also: the cultural behemoth that was Luis Fonsi, Daddy Yankee and Justin Bieber’s “Despacito” remix.

Luis Fonsi (left) and Daddy Yankee perform "Despacito" at this year's Grammy Awards.

Luis Fonsi (left) and Daddy Yankee perform “Despacito” at this year’s Grammy Awards. | AP