In common vernacular Aesthetic as a noun has often come to refer to a collection of visual and audio themes designed to make a particular point, signify a time or movement, evoke a complicated and multifaceted emotion, or simulate another state of being.
So examples of these "Aesthetics" in the common zetigeist might be, say, something like
Making a particular point: Cyberpunk is a portrayal of the future from a pessimistic lense, often expressing countercultural ideas and politics. A lot of the punks originally were about this in some way before the genres became a lot more broad aesthetics that encompassed the other categories.
Signify a time or movement: This one is fairly straightforward and one of the ways people normally seem to talk about aesthetic even if they're old. Glam Rock, the Rennaissance, and Soviet Communism all have a very recognizable aesthetic that you can see or hear almost instinctively whenever you think about them unless you're a blasphemous husk like Celicni, and even then he probably at least has data to remind him of what these times looked like though he cannot feel and comprehend it.
Evoke a complicated and multifacetted emotion: a common joke in modern circles is to take images or experiences and then make extremely specific and exagerrated metaphors or similes about how they make you feel, and that's sort of what this is about. There's a difference between being sad in a way that makes people listen to old country music for catharsis, and being sad in a way that makes people listen to emo music for catharsis, and it's possible to be a person that experiences both rather than one or the other. You probably have had "Playlist for 18th century villains watching the downfall of their enemies" or whatever come up in your recommended, and this is exactly that kind of thing.
Simulate another state of being: This is kind of the culmination of all the previous things, but with a sort of emphasis on almost ritualistic immersion in a time and place you are not, and you don't even necessarily have to go all out to do this. Listening to sea shanties while in an imaginitive mood in order to sort of escape the drudgery of repettitive physical tasks can be one thing, working out to "viking music" or fantasy metal- Or using the Star Trek ambient ship noise to fall asleep, are all examples of this.
There are also personal aesthetics, which become especially prevalent in teenage girl culture and by extension all of the ones we're going to be talking about in this internet anthropology lesson. To put a more wholesome and less narissist-accusatory spin on it than the analyses of this interpretation of aesthetic currently do, these would be all the little extrapersonal things that remind people of you personally- and everyone has one of these. Knit blankets, the green bay packers, and certain manners of speech remind me of my Grandma, for example. Necromancy and shadowy robed figures at this point are linked inextricably with Endmaster in CYS culture to the point where we wound up "finding" him in some of MHD's entirely unrelated art that one time. During the Tumblr Golden Age, (which was truly the cosmopoolitan hegemon of Teenage Girl Culture at one point during the 2010s and is the most obvious and direct ancestor of Current Teenage Girl Culture in the places where its diaspora have spread, notably Tiktok) however, there became a cultural consciousness of personal aesthetic as everyone could also personalize their blogs, and with this awareness often came people trying to control or at least fine-tune the way they appeared to other people and the emotions they evoked in other people as an aesthetic themselves. Their brand, so to speak. I'm certain you've heard someone in the 2010s meme by posting some funny inexplicable image and being like "this is my aesthetic" and that's sort of the only way I know to get the feeling across. This notion of personal aesthetic combined with all the previous ones is how you get these almost deliberately constructed subcultures at the intersection between fashion, music, and interior design, like "Dark Academia" and "Cottagecore" which, while cringy to us, are some of the only extant ways subculture has kind of carved out its survival in the internet age.
On Tiktok people, young girls in particular, are especially aesthetic-conscious due to the highly filtered and choreographed nature of its content. In the snippet of 15 seconds, an especially creative and ambitious person can make their life appear to be almost anything they want it to be. Naturally a lot of people crave this fantasy and so put a great deal of work into building their personal aesthetic.
Floptok Culture surrounds sort of comedic parodies of tiktok celebrities and forms this kind of rebellious teenage girl subculture within rebellious teenage girl subculture. They are like ironic fans of ironic celebrities except not quite ironic. The way that they use aesthetic to mean stuff like fashionable, good, and/or jurisprudentially cleanly, is sort of a parodic and deconstructive way of both making fun of people who think like that, but also acknowledging that they are not free of that pattern of thought. Holy shit 870 words is too much I'm ending this essay now before I lose it.