Whether it was a late-night television commercial or a Walmart display, chances are you've come across Now That's What I Call Music! These greatest-hits compilation CDs debuted in the U.S. in 1998 and feature track lists made up of the hottest singles in music. And while the 69th installment was released earlier this year, the brand is actually much older across the pond. For a closer look at this best-of series—including why a pig was involved in its creation—check out our liner notes.

  1. Now That's What I Call Music! was created in the UK.

The back cover of the first Now That's What I Call Music! album, which included a picture of the vintage poster that inspired its name.Bradford Timeline, Flickr // CC BY-NC 2.0

Now That's What I Call Music! didn't originate in the United States. The brand actually dates back to 1983, when UK record labels Virgin Records and EMI teamed up to create a compilation of popular acts under contract, like Phil Collins, Tina Turner, and UB40. The idea was that the bigger names would draw attention to lesser-known artists included.

  1. The name Now That's What I Call Music was inspired by a poster of a pig.

While executives at Virgin were brainstorming possible titles for the release, they took note of a poster for Danish bacon that Virgin founder Richard Branson had bought from a general store as a novelty. The poster featured a singing chicken and a pig who was apparently happy with what he was hearing. Above the pig, a caption read: "Now. That's what I call music." That's what Virgin decided to call the record.

  1. Each Now That's What I Call Music! album is meant to be a time capsule.

The first Now That's What I Call Music! album, which was released in November 1983.Bradford Timeline, Flickr // CC BY-NC 2.0

The first UK installment of Now That's What I Call Music! sold 900,000 copies and was a huge success. From that point on, three albums were released annually, and the selection process has largely remained the same. Jeff Moskow, who oversees the tracks for the U.S. edition, told TIME in 2014 that the brand's priority is to provide a snapshot of popular music in a given era. Moskow looks at radio play, album sales, and streaming figures as well as social media followings to determine what's relevant in the culture. "You're supposed to be able to grab Now 4 or Now 25 or Now 50 and appreciate the music of that particular moment," he said. "Now is meant to give you that picture."

  1. No one was sure Now That's What I Call Music! would work in the U.S.

Now spent 15 years in the UK before Sony and Universal, which jointly produce the albums, decided to bring it to the United States in 1998. At that time, U.S. retail outlets didn't necessarily have shelf space devoted to compilation CDs—plus, different record labels rarely worked together. Producers had to convince them that including popular songs wouldn't cannibalize an artist's own album sales—instead, it would likely have the opposite effect, bringing new listeners to acts they might not have been exposed to otherwise.

  1. Not all artists are interested in participating in Now That's What I Call Music!.

In order for a track to appear on a Now release, record labels and artists need to give their consent. Speaking with Thrillist in 2017, Moskow said that younger artists tend to be more enthusiastic about getting their music out to a wider audience, while more accomplished artists who have perhaps been around a little longer are more "pensive" and reluctant to offer permission. Bruce Springsteen is one example of an artist who has yet to say yes to Now.

  1. There's no cursing allowed on Now CD tracks.

When a track has been selected, producers are careful to obtain the radio edits, which typically have any expletives present on the album version removed. The reason is the target audience of Now can skew heavily toward adolescents. The compilations are often played in cars for kids to sing along to, and cursing might invite the wrath of parents.

  1. There's a reason no artists appear on Now That's What I Call Music! covers.

Now That's What I Call Music! 5, which was released in the U.K. in August 1985.Bradford Timeline, Flickr // CC BY-NC 2.0

The first Now release in the UK featured a collage of some included musicians (Phil Collins's likeness was on there twice—both as a solo artist and as a member of Genesis), and the next three also had promo shots of artists like David Bowie, Annie Lennox, Culture Club, Queen, and Lionel Richie. But starting with the fifth installment, which only showed the early-days mascot pig, subsequent releases have almost always featured a graphic instead of any artist photographs. That's because it's already a challenge to secure permission to license songs: Any last-minute problems with getting approval for a photo would only complicate the process and could conceivably delay the album's release.

  1. Some songs aren't the right fit for Now compilations.

Now tracks are typically divided into three categories: current hits, recent hits, and songs that might be hits in the near future. For the most part, all of the selections are generally upbeat. When Moskow pursued the politically charged Grammy winner "This Is America" by Childish Gambino, both he and the record label agreed that it was ultimately too potent and serious for the collection.

  1. There's a lot of thought put into the track order.

The jewel case for the U.S. version of Now That's What I Call Music! 4, which was released in July 2000.Christo Drummkopf, Flickr // CC BY 2.0

Curating a Now release is more than just selecting a bunch of songs. Moskow spends a significant amount of time putting the chosen songs in a precise order. Faster and more upbeat tracks typically start the albums, with slower ballads in the middle. If a country song is included, it's usually on the back end (such as Jason Aldean's "You Make It Easy" as track 16 of 17 on 2018's Now 66. Now also tends to minimize any pauses between songs so it feels like a continuous stream of music. Most songs begin on what would have been the next beat of the one that just ended.

"Anyone who's ever made a mix tape or really worked on a playlist knows what that art is," Moskow told TIME. "It's trying to make the music make sense, taking a bunch of different types of music and a bunch of artists and putting it in an order, a sonic tapestry, that makes sense for the listener."

  1. Now is still selling strong thanks to cars.

In an era of streaming music, it's hard to imagine people reaching for physical media. Yet Now continues to sell CDs on both sides of the pond, and there's a good reason why. Many cars are still equipped with CD players, making a Now disc an appealing option as a driving soundtrack. A physical disc is also an impulse purchase and easy to grab when a person is in need of a quick gift.

  1. Now That's What I Call Music! once thought of doing away with the numbers.

With Now celebrating more than 100 installments in the UK (Now 102, which features two recent hits by Ariana Grande, comes out in April 2019) and 69 in the U.S., it seems unthinkable that the brand would have ever wanted to move away from the numbering system. But early on, there was concern labeling a record "21" or "40" might lead consumers to believe it was something outdated. The numbers actually became an asset, and people now identify their first Now purchase with a number. To date, the series' most impressive figure is 250 million, the total number of albums sold worldwide since its launch in 1983. In the U.S., Now has sold more than 100 million copies. Not bad for a bunch of mixtapes.