Oh baby, baby.

Twenty-five million copies sold and 24 years later, Britney Spears' debut album, ...Baby One More Time, is still the pop icon's most successful album ever. And it makes sense, seeing as how the 41-year-old's first outing lead the resurgence of teen pop music and defined a generation.

Spears, then just 17 and somewhat known for her time on The Mickey Mouse Club as a child, became the most famous teenager in the world...and since then, the world has never stopped being transfixed by the princess of pop. (Most recently, fans across the globe supported the icon as she broke her silence on her terminated conservatorship and much more in her bestselling memoir, The Woman In Me.)

But did you know her iconic "...Baby One More Time" single, one of the most successful songs of all-time, almost went to another artist? ...Baby One More Time was released on Jan. 12 and, thanks to the monster success of that first single and its accompanying music video of the same name, went on to become the second-best-selling album of 1999—and is still one of the best-selling albums of all time.

And in an era where music groups (TLC, Backstreet Boys, The Spice Girls, 'N Sync, etc.) were dominating the music scene, Spears' solo success at such a young age was almost unprecedented and helped lead the charge for teen queens such as Christina Aguilera, Mandy Moore and Jessica Simpson. 

To pay proper respect to the genre-defining album, we're going back to 1999 and revealing some secrets about Spears, ...Baby One More Time and that schoolgirl outfit...

Britney Spears' first major hit, of course, was "…Baby One More Time," but the song almost went to a different artist, after famed songwriter Max Martin, one of Spears' longtime collaborators, wrote it with an R&B flavor in mind. He sent it to TLC.

"I was like: ‘I like the song but do I think it's a hit? Do I think it's TLC?'" T-Boz told MTV in 2013. "Was I going to say ‘Hit me baby one more time'? Hell no!"

After TLC passed, the song was then offered to Robyn, but it didn't end up working out. Spears' record label Jive then set up a meeting between their young star and Martin. "I was pretty young at the time, so I was nervous," she recalled, "but he was so nice and put me right at ease."

The rest, as they say, is history.

After "…Baby One More Time" became an immediate success, the team quickly got to work on making a music video worthy of the song.

Director Nigel Dick revealed on his official site his original idea for the video was very different and "sucked—so the label put me back on the phone with Britney who told me she wanted to make a video where she was stuck in a classroom thinking about boys."

Spears told Rolling Stone, "They had this really bizarre video idea, this animated Power Ranger-y thing. I said, ‘This is not right. If you want me to reach 4-year-olds, then OK, but if you want me to reach my age group …' So I had this idea where we're in school and bored out of our minds." (The main love interest in the video was played by Spears' cousin, Chad Spears, by the way!)

As for the iconic schoolgirl uniform Spears sported? Like the concept of the video, It was all her idea. "When we'd decided we were shooting in a school the stylist asked me, ‘What do you think Britney should wear?' And I replied: ‘Jeans, sneakers, T-shirt,'" Dick stated on his website. "Britney's comment was: ‘Don't you think I should be wearing a school uniform?'"

So that quote she gave to Rolling Stone? It went along with a rather racy and headline-making cover image, which featured Spears in a bra and underwear, lying in bed while holding a Teletubby. She was not that innocent. And some were downright shocked by the small town Southern girl's sexy turn.

"If I had a 17-year-old daughter she would not be walking out of the house like that," one person told Inside Edition after the cover's release, while another said, "I think it's shameful."

But Spears knew what she was doing.

"When we shot together...I was talking to Britney, I said, 'We don't want you to be another Debbie Gibson, another goody two-shoes,'" photographer David LaChapelle said at the time. "I said, 'We're shooting for Rolling Stone, which has an older readership, which may resent having this teenager on the cover...let's do something for them. Give people something to talk about...and something that sets you apart from everybody else. Let's do something a little provocative.' She was up for that. it was coming from her. We knew what we were doing when we did those photos...we knew they were going to cause a little bit of a ruckus. We didn't quite know it was going to be that big of a ruckus, but I think it was smart because people really learned her name after that and really gave people something to talk about." 

Just as her career was taking off, Spears' two-year relationship with Reg, her first boyfriend, came to an end.

"It wasn't that I was changing," she explained to RS. "We broke up before any of my success had happened. He became insecure with himself, I felt. I wasn't gonna do anything—I'm a straight-up, honest person, and if I was gonna do something, I'd tell him before I'd do it and end the relationship. I was really head over heels in love. I don't think I'll ever love somebody like that again. I just woke up one day and click, it was gone."

As well all know, she would go onto love somebody like that again.

After Spears served as the opening act for ‘N Sync's tour just ahead of her debut album's release, headlines and fans speculated (and wished) she and Justin Timberlake, her fellow former Mickey Mouse Club Mousekeeter  were dating.

"No, it's not true," Spears told an inquiring fan who asked about the rumors that she and Timberlake had gone out during Much Music appearance. "I guess because we were on the Mickey Mouse Club together...people are going to start rumors, but no, it's not true."

Of course, it was eventually revealed to be true, with the pop power couple going on to date for three years...and we've got the denim-filled photos to remember it by forever.

Originally, Spears, now considered the Princess of Pop, wasn't really all that interested in making pop music. In an interview with Rolling Stone, she admitted she envisioned herself singing "Sheryl Crow music, but younger—more adult contemporary."

Her record label, Jive, wanted to pair her with more pop-leaning producers and writers, a decision she didn't push back on. "It made more sense to go pop, because I can dance to it," she told the magazine. "It's more me."

"(You Drive Me) Crazy" was the album's third single, with the pop song also featuring prominently on the soundtrack for the teen rom-com Drive Me Crazy, starring Sabrina the Teenage Witch's Melissa Joan Hart and Adrian Grenier, pre-Entourage fame.

The music video's concept was Spears' idea, with the singer telling MTV in 1999, "It would be cool to be in a club, and we're dorky waitresses, and we break out and start dancing."

Given the song's inclusion on the Drive Me Crazy soundtrack, the plan was for the movie's two stars to make a cameo in it. The problem? "The big issue is that Adrian Grenier did not want to be in the video," director Nigel Dick told MTV News in 2009. "So, I was given instructions to ring him up and make sure he appeared in the video. I said, 'You know what, Adrian, I just think it would be great for your career, and Britney's a great girl and she's fun to work with.' Eventually he came around."

Before recording "Born to Make You Happy," Spears asked the songwriters to change some of the lyrics, which she felt were too suggestive for her at that point in her career.  

"I asked them to change the words to 'Born to Make You Happy.' It was a sexual song," she told Rolling Stone. "I said, 'This may be a little old for me.' Because of the image thing, I don't want to go over the top. If I come out being Miss Prima Donna, that wouldn't be smart. I want to have a place to grow."

Spears experienced a minor tabloid scandal after the release of the music video for the album's fifth and final single, "From the Bottom of My Broken Heart," when it was revealed that its director Gregory Dark had previously worked on adult films.

"It's time to admit that the new teen pop isn't heavily coded XXX made for and marketed to teenagers," a write-up in LA Weekly at the time claimed. "In fact, it‘s explicitly made and marketed as such."

A rep for Spears at the time said, "As far as I'm aware the director just does music videos. This is a video for young teenage girls and not sexy at all."

And, in a somewhat ironic twist, the director told Entertainment Weekly they actually hired him to tone down her image for the video.

"They wanted to re-image her a bit [from the naughty schoolgirl of "...Baby One More Time"]," Dark, who also worked with Mandy Moore on a music video, said to the magazine. "They wanted a much more story-oriented video without dance, one that was serious and emotional."

Spears was forced to postpone her "Sometimes" music video and cancel an appearance on The Tonight Show With Jay Leno when she injured her knee during dance rehearsals for the video, which required intense physical therapy.

Five years later, Spears would require arthroscopic surgery on her knee after reinjuring it, postponing one of her tours.

While she went on to open for 'N Sync (and date one of its members), the group's direct competition, Spears' debut album contained a spoken message from the singer promoting Backstreet Boys, who were also signed to her record label. At least on the original copies of it.

"'The Beat Goes On' fades out to make way for Spears to say 'Thanks' for buying and listening to her album," MTV wrote in their 2010 take after re-listening to ...Baby One More Time. "There is then a sneak preview of some music from another group on her label ... the Backstreet Boys! So there's a great piece of trivia for you: The last song heard on Britney Spears' debut is actually Backstreet's 'I Need You Tonight.'"

This story was originally published on Saturday, Jan. 12, 2019 at 3 a.m. PT.