we all know what fanfiction is, and even if you've never read it before you could probably guess based off the name alone. fanfiction is fiction made by fans. fans write stories about their favourite characters and post for other fans to read.
i started reading fanfiction when i was just shy of 14 and it has fundamentally changed my life. i am not exagerrating in the slightest when i say that creating an ao3 account has probably had one of the largest impacts on me as a person. without sites such as ao3 i would not be as involved in fandoms as i am now. i started reading voltron fanfiction in 2018 and despite the show ending and the fandom dropping off i am still reading voltron fanfiction to this day. i never stopped. i am still in this fandom and i attribute that to fanfiction.
there's something so unique about fanfiction. whereas for other fan cretions such as fanart which is generally better recieved by the general public, fanfiction is usually just seen as 10 years writing cringy y/n fics or just pure smut. and that could not be further from the truth. i have more favourite fanfics than i do favourite books, they are that well written and thought out. if there is something i didn't like about canon, chances are there is going to be a fanfic fixing or improving that aspect. and its fucking amazing. fandom members will somehow unanimously agree on something and it becomes a fandom staple. examples are the voltron fandom using altea or daibazaal (planets) as school names for college/high school AUs or saying that keith's dad's name is 'texas' because we never got an official name and he sounded southern. or one fic getting popular and then popularising a headcanon they included and suddenly you can't figure out if its canon or not because suddenly everyone is using it. i have no idea whether or not one of lance's nieces(?) is actually called cleo but dirty laundry said she was and everyone else agreed.
i am definitely more of a reader than a writer but i have still dabbled in writing my own short one-shots (see: here). AND ITS FUN!! you get to write about the characters you already love so much and play with the plot/setting/whatever the hell you want. there are no limits. fanfiction is literally a love letter to a specific media. (sometimes hate letters cause canon be fucked up sometimes but its the same sentiment)
i've started writing a whole essay, references and all, about why i love ao3 so much and why its objectively the best fanfiction site. i never finished it but i got the main sentiments done. you can read it here