Attempting to define exactly what a boy band consists of can be as frustrating and fruitless as trying to explain the difference between an album and a mixtape: As soon as you think you have the rules consistent, you immediately think of three obvious exceptions that nullify your thinking entirely.

Ultimately, we at Billboard decided for the sake of our sanity that it was easier for the purposes of our Boy Band Week -- and particularly our list of the 100 Greatest Boy Band Songs of All Time -- to not even bother with trying to form a bulletproof definition that the artists between all 100 of our songs would have to fit perfectly. Rather, we're taking it on a case-by-case basis, looking at each group individually and determining whether or not they come close enough to our perceived boy band sound, image and backstory to qualify.

Below, Billboard staffers Andrew Unterberger and Joe Lynch take a look at seven of the most troublesome cases of borderline boy bands and come to a tough-but-firm decision: Are they a boy band or not?

The Beatles

Andrew Unterberger: The Beatles are an interesting boy band debate, because either they're the furthest thing from a boy band, or they're the most important boy band there's ever been. I dunno if there's much room for an in-between interpretation.

For me, I think they sorta have to be considered one, at least at first -- I still believe the most important qualification for a boy band is in the way they're received by their general fanbase, and the Beatles essentially set the template (and the bar) there for audience screaming, for favorite-member debating, and for -mania suffixing. And of course, their early songs are about as pop as pop (or at least rock) gets, and could've been seamlessly reinterpreted for New Edition or Backstreet Boys hits with minimal re-interpretation.

(Interestingly, though, I can't think of a single notable boy band cover of a Beatles song -- Boyz II Men doing "Yesterday" might be the closest. Too daunting to take on the GOATs, perhaps?)

Joe Lynch: Yes, they certainly demonstrated the economic potential for a boy band (they are the reason the Monkees exist, for instance) and they also set the precedent for how difficult it is to define a boy band. While few under the age of 65 mainly associate them with "She Loves You," the first couple albums were undoubtedly the foundation of the modern boy band movement. But were those albums best defined as "boy band music?" Probably not.

I feel like they were arguably a boy band in terms of marketing for a couple years, then inarguably not a boy band for the bulk of their run (a number of outfits would follow in those footsteps). For my money, I'd say the self-awareness of A Hard Day's Night and its meta film marks the end of their boy band-ish era.

Verdict: Boy band (But only at first)

Boyz II Men

AU: It's tough for me to think of Boyz II Men as a "boy band," mostly because when I was a ten-year-old watching the "I'll Make Love to You" video, they could've been in their 40s already for all I knew. Being a boy band is all about youthful exuberance, and the Boyz were much more dedicated to adult vibin' -- calling them a boy band would be like calling the Temptations or Harold Melvin and the Blue Notes a boy band. Not all male vocal groups that dress similarly can be boy bands.

Still, they were New Edition acolytes, even naming themselves after an NE deep cut, and their first album -- "Motownphilly" in particular -- definitely has some boy band energy to it. So I can see the argument, to a point.

JL: Not a boy band. From the get-go they presented themselves with a level of maturity that, say, New Edition or the Beatles didn't upon first blush. I think you'd have to bend over backward to argue they're a boy band either in terms of sound or marketing. They were sexy and in control – not cute, inoffensive boy-next-door types.

Verdict: Not a boy band

5 Seconds of Summer

AU: "They can't be a boy band, they play their own instruments!" This argument drives me nuts -- as if the Jackson 5 didn't play their own instruments, as if a term with the word "band" in it somehow suggests a group with no musicians allowed. It is true that at a certain point, a band of all-boys does just become a band, but when they're a bunch of extremely successful and good-looking teenagers playing power-pop jams -- when they inspire mania enough that even the friggin' bass player briefly becomes a celebrity -- they still make the boy band cutoff for me. Besides, what is "She looks so perfect standing there in her American Apparel underwear" if not the "You looked like a girl from Abercrombie & Fitch" for the next generation?

JL: Definitely a boy band. No slur on their music, but their popularity is attributable at least as much to aesthetics as sound; the way their fandom approaches them is closer to how Directioners looked at 1D than how Hot Topic regulars regarded Blink-182. Sure, 5SOS cite the latter as an influence, but they toured with the former. It's not like pop-punk fans made 5SOS big – maturing Directioners looking for something more dangerous did.

Verdict: Boy band

Hanson

AU: The best argument against Hanson as a boy band might be that they never broke up -- breaking up for the first time is about as essential a part of the boy band circle of life as forming in the first place. It speaks to the fact that despite forming as a trio of teenage siblings, they were never prefabricated: They were a genuine band of brothers, growing into and out of their celebrity status and never losing sight of the music and of each other being the most important things. And their music evolved with them, too -- they might be one of the only boy bands ever whose most essential album isn't even one of their first three.

Still, all that said: They were three teenage males who made the poppiest music imaginable and were rewarded with millions in sales to millions of hysterical fans for it -- and along with the Spice Girls, they were also the obvious stage-setting act for the entire TRL era. So I'm pretty torn here.

JL: On one hand, Hanson's entire post "MMMBop" run would argue against them as a boy band. On the other hand, "MMMBop" was the inescapable culture-saturating hit that they're best remembered for, and that's as boy band as it gets – not to mention a great reminder that boy band songs needn't be written by Swedish pop masterminds and played by middle-aged session men. Like it or not, Hanson will always be best remembered for that jam, and that period was inarguably boy band – I mean, that Christmas album!

Verdict: Boy Band (at first)

112

AU: The toughest part of this exercise might be in deciding where the mid-'90s R&B groups cut off in terms of boy bands vs. adult vocal groups. For me, 112 might fall just on the former side of the debate: They were high school friends and started recording young, they were overseen by a Svengali in Puff Daddy, they danced at least a little bit, and though Slim was pretty obviously the vocal focal point, it felt less like a totally top-down group structure than, say, Dru Hill.

The one thing holding me back here is that it's rare, to say the least, that a boy band would produce a song as legitimately adult-sexy as "Cupid." But then again, they also did "Peaches & Cream," so maybe it cancels out.

JL: They're certainly not a quintessentially boy band outfit, but I think having Puffy as the guiding force pushes them in that direction, as does the sweetness of their vocals and the fact that they were more heartthrobs for teens and tweens than any full-grown adult's proper crush.

Verdict: Boy band

The Monkees

AU: I think that if the boy band timeline doesn't conclusively start with the Beatles, it pretty much has to start with the Monkees. They were basically The Beatles -- as cute, as individually packaged, as perfectly poppy -- but factory-assembled, the model for generations of svengali'd boy bands to follow. And -- much to Marge Simpson's eventual horror -- they didn't even play their own instruments! Certainly, once they essentially became sentient and entered their dropping-acid-with-Jack-Nicholson phase, they had outgrown the tag, but for those first couple years of cross-platform omnipresence, The Monkees were as boy-band-y as they came.

JL: Totally agree – the Beatles demonstrated the economic opening, and the Monkees were the template for how industry execs – versus artists themselves – could make the most of this profitable niche. And while we've seen boy bands since that follow both paths, the factory-assembled group of poster pin-ups types has proven the more durable model. The Monkees are absolutely essential for any serious boy band discussion.

Verdict: Boy band (before self-actualization)

Brockhampton

AU: It only took about 60 years, but finally, we have a group that actively refers to themselves as a boy band -- which, previously, had been about as common as a music fan self-identifying as a hipster.

Of course, in Brockhampton's case, it comes as something of an act of subversion, as the hip-hop collective would not meet anyone's traditional definition of a boy band -- but with genre walls coming down and music fan minds opening up to an unprecedented degree in the year of our lord 2018, who's to say that an exciting group of young wiseass rappers with awesome branding sense and rabid fan enthusiasm can't, in fact, be the best boy band since One Direction? I'm not sure if they're there yet, but I wouldn't rule out the possibility.

JL: No way they're a boy band. It's either irony or a clever marketing ploy to star in a Viceland show called American Boyband, but their musical sophistication and lyrical maturity seem like immediate disqualifiers. And if not that, take the fact that they're not being marketed as adorable, safe potential boyfriends for tweens, but rather as an exciting, experimental collective of artists. If they're a boy band, then we should consider Baltimore boy band mainstays Animal Collective for this list.

Verdict: Not a boy band