I think everybody has heard of fanfiction, but people have many different ideas about and opinions of what it is. In Media and Social studies there has been conducted research on fanfiction. One of the people who does that is Bronwen Thomas, a professor. Her current research topics concern exploring creativity and storytelling and how readers and writers communicate in digital spaces. The definition Thomas uses is:
The term fanfiction (sometimes abbreviated as fanfic) refers to stories produced by fans based on plot lines and characters from either a single source text or else a “canon” of works; these fan-created narratives often take the pre-existing storyworld in a new, sometimes bizarre, direction.Bronwen Thomas. “What Is Fanfiction and Why Are People Saying Such Nice Things about It??” Storyworlds: A Journal of Narrative Studies 3 (2011): 1. https://doi.org/10.5250/storyworlds.3.2011.0001
I agree with her definition but most of the time fanfiction is thought of as text. And in my opinion, besides written text, fan fiction also consists of fan-made edits (videos and images) and digital art. In this blog when I discuss fanfiction I will mostly mean written fanfiction as the platforms I discuss are for written fanfics.
I first came across fanfiction on Tumblr several years ago. I had fallen into a rabbit hole of a fandom and saw a prompt. A ‘prompt’ in fanfiction, as I understand it, is a piece of fiction about a certain topic/narrative that a reader/consumer requests and is then made by a creator. A creator can also make different prompts about a certain topic e.g. every day of the month October a Halloween prompt.
Where do you find fanfiction?
Fanfiction has been around for quite some time. It dates back to the science magazines from the 1920’s. Nowadays most people consume their daily dose of fanfiction with the help of an internet connection. The three most popular platforms for fanfiction are fanfiction.net, Wattpad and Archive of Our Own (or AO3). A less-know platform is DeviantArt. That is more for digital art and visualizations of fanfictions. Other digital platforms such as the social media Tumblr and Twitter are often used to spread fanfics from these websites.
Digitalization and popularity
Millions of people consume fanfiction and digitalization has made that possible according to Thomas. 
It has brought many great things for the people who read fanfiction. It is easily accessible as it can be accessed on multiple devices and anywhere with an internet connection. Like many things on the internet it can be viewed anonymously. It reaches a big audience, people from all over the world . Many creators collaborated and made friends. It also creates communities: of writers in the same fandoms, of readers of the same type of content. It creates a space for creative interaction between online and offline selves. 
There is a great variety in content: Literally whatever you can come up with, it has been made.
Many people read the same things or had similar experiences and created memes. Mostly about bad or filthy fanfictions but many people can relate. Below a TikTok link with an example of a meme.
The platforms used to post fanfiction on can also be used for interaction between creators and viewers, e.g. when people ask for prompts or they leave a comment on a story.
A big part of reason fanfics are so popular is the fact that it diverges from the canon. Your favorite characters are explored and different stories and people are represented. More POC and LGTBQ+ stories and experiences are shared and you can lose yourself in those worlds. It is important that there is a place for these people to make their favorite characters and stories a safe space for themselves and put themselves in those tv-shows, books or films.
While I am a big fan fanfiction I do have to say there are some downsides.
You can com into contact with very graphic content from a young age and because some people have a certain understanding of what fanfiction is they could have some prejudice towards the people who read and write it.
Despite this the reason I love fanfiction is the fact that there is content there for everybody and it created a sense of belonging because I found people who got excited over the same as me. I could also explore parts of my identity while maintaining anonymity. This would not have been possible if not for digitalization.
PS: An observation I made that is related to the idea people have of fanfiction and its community:
I think a connection can be made about the platform you frequent and the content you come across or consume. Wattpad and fanfiction.net have that is more aimed and made by younger creators. It is immature and totally unbelievable (which I get is sometimes the point) combined with bad narrative and often grammatical and spelling errors. Way more badly written fantasy etc. While AO3 overall has more mature content and better written stuff. And don’t get me wrong I think that is great that people have the opportunity to explore their form of expression and writing style but it is something I noticed. When I got older I started to switch platforms.
 Erin Blakemore, Fanfic as Academic Discipline, 2017
 Bronwen Thomas, “What Is Fanfiction and Why Are People Saying Such Nice Things about It??” Storyworlds: A Journal of Narrative Studies 3 (2011), 2
 Bell, Alice ; Ensslin, Astrid ; Rustad, Hans. “140 Characters in Search of a Story: Twitterfiction as an Emerging Narrative Form.” In Analyzing Digital Fiction, 104–118. Routledge, 2014, 95
Blakemore, Erin. Fanfic as Academic Discipline, 2017
Thomas, Bronwen. “What Is Fanfiction and Why Are People Saying Such Nice Things about It??” Storyworlds: A Journal of Narrative Studies 3 (2011): 1–24. https://doi.org/10.5250/storyworlds.3.2011.0001
Bell, Alice ; Ensslin, Astrid ; Rustad, Hans. “140 Characters in Search of a Story: Twitterfiction as an Emerging Narrative Form.” In Analyzing Digital Fiction, 104–118. Routledge, 2014. https://doi.org/10.4324/9780203078112-15
Milli, Smitha and Bamman, David