AO3 is best known for fic, but the site also allows art, videos, and many other mediums to be shared. Since the site can only natively host text, these kinds of works have to be hosted on another platform and then embedded in a work.
Beyond creative works, the site also allows people to post meta. Detailed character analysis, commentary on fandom trends & stats, and other extended explorations about fandoms all belong to this category.
The information that AO3 requires to post a new work is:
Title
Rating
Fandom
Archive Warnings
Language
Beyond those elements, a person is free to include as little or as much information as they want. Largely, AO3's ethos seems to be enable creators as much freedom as possible on how they want to label their own works.
To facilitate those goals, the site even offers "reader beware" options for many of these elements. Ratings has "Not Rated". Fandom tags have "Unspecified Fandom". Warnings has "Creator Chose Not To Use Archive Warnings". Using any or all of these options on a work is both valid and intended use of the site.
There has been a recent trend in fandom to include potential squicks or triggers in the additional tags, since more tags increases readers ability to exclude unwanted works as well as increases the search-ability/find-ability of a specific work. Alongside this trend, I've noticed the perspective that choosing to be information-lite is rude or site abuse. It may be the norm in some fandom communities, committing a social faux pas is not the same as breaking a site rule. AO3 encourages people to tag according to their personal preference.
This expectation is is heavily fandom and person dependent. There's plenty of good reasons to opt-out of including extra information. Sometimes that good reason is 'if I stare at the posting page any longer I won't share the fic at all'.
Misconception: Adding your work to a collection means it can be unrevealed without you knowing!
This used to be true. It isn't anymore. It hasn't been true for a while with more and more updates removing the function-abuse potential as time passes.
The short version for anyone worried is that works cannot be added to anonymous collections or unrevealed collections by someone other than the creator. This has been true since 2017. If a work is already in a collection and that collection later becomes anonymous or unrevealed, an email is immediately sent to you with instructions on how to remove your work from that collection. This was deployed in 2020. This is why it's important to keep your AO3 email up to date.
For anyone who is curious and wants to know the full time and all changes that have been added overtime. Well, I was curious and dug through AO3's changelogs:
In 2016, AO3 added the ability to for collection owners and maintainers to invite works to their collection (change log 2016-06-16). Previously, only creators could add works to collections. It looks like this function was implemented around 2016-04-18 based on this announcement post.
However, this had some unwanted interactions. Maintainers could change the settings for a collection and that change would retrospectively be applied to every work and also if a new work was added to that collection, it would automatically inherit that status without the creator realizing. That combined with the fact, at the time, that every account allowed works to be added to collections without prior approval meant that a malicious actor could anon or unreveal a collection and make someone's work unseeable to them. (The fact that anon or unrevealed works don't show to a creator has also been fixed for ages so you should be able to find these works under the collection tab on your page.)
This is the reason why people always tell new AO3 users to reject collection requests. This is the scare they recall.
In 2016, AO3 stopped works from automatically being added to anonymous or unrevealed collections. Adding to work to such a collection would need the creator's permission first. This was announced in the same chang log the update to allow maintainers to invite works to collections was made. (change log 2016-06-16)
Since this changelog was about two months after the announcement of this ability, AO3 prioritized closing the main exploit possible by this bug.
In 2017, AO3 decided to make it impossible for works to be added to anonymous or unrevealed collections entirely except by the creator of the work (change log 2017-10-12). Even if someone enables "Automatically agree to your work being collected by others in the Archive.", the work will not be added. It is just not possible for a work to be added to a collection that is already set to anonymous or unrevealed without the creator doing it themselves.
In 2019, AO3 discovered that their fix from 2016 didn't apply retrospectively. This meant that if any works were floating in permissions limbo in 2016 then they would have been hidden. Good news: when the fix was applied it was determined no works were affected by this potential exploit. (change log 2019-08-16)
In 2020, AO3 made it so creators automatically receive an email if a collection was later anonymized or unrevealed a collection. This email also contains information for how to remove works from such collections. (changelog 2020-03-18)
In 2023, AO3 changed the default setting of user accounts. Now everyone has to opt-in to works being added to collections. The reason for this change is implied to be the continued concerns people have around collections. (change log 2023-03-31)
In short, the main exploit was partially addressed within two months and fully resolved in about a year and four months. As for maintainers later being able to make changes without creators' knowledge, this was addressed in 2020. It was likely there were other fixes between 2017 and 2020 that addressed related issues but it didn't show up on my quick skim.
Misconception: A fandom, character, or relationship tag should only be used on safe for work, or works acceptable to show minors.
I've seen many variations on this idea that works need to be "removed from the feed" since:
the fandom community or canon includes people who are under 18
the creator doesn't like smut
the tag should only include non-problematic fic
the work is too weird to be in the tag
AO3 is an Archive. The tags exist to help creators organize their works and for readers to filter on the tags creators choose to use. The idea that specific works don't belong to a tag is contrary to the spirit of archiving content.
I suspect that this line of thought comes from people applying social media etiquette to AO3. On a lot of social media sites, when a post is tagged with specific tag, there's a non-zero chance it will be inserted into someone's personal feed whether they've marked that tag as an interest or not. This means a person is having unwanted content shoved in their face. In this environment, it's polite to avoid tagging specific types of content since you're not sure where it will reach.
However, an AO3 tag does not work like a personalized feed. With a personalized feed, filters are applied before you see something. An AO3 tag will show you everything tagged with it and then it is up to you choose to to apply filters to narrow the search results.
The tags are intended as metadata, so they're meant to show every work that relates to the tagged topic (if the creator wants to include it). Whether a specific person finds a work unwanted should not impact whether the work shows up in the tag.
Since AO3 has exclusion filters, that means the same mechanism that allows people find works can be used to remove unwanted works from a search.
Misconception: OTW's Board candidates are pre-vetted.
All someone needs to become a candidate is to meet the Election team's eligibility requirements.
These conditions are fairly easily to meet. All someone has to do is tell an Elections member they want to run. If that volunteer has volunteered for at least 9 months, has an active OTW membership, and is over 18, they're a candidate after they ask. There's a few other requirements but that's the bulk of it: https://elections.transformativeworks.org/becoming-candidate/
The process of determining whether someone is the good fit is the election itself. The candidacy declaration is pretty straightforward likely to encourage as many people interested in the role to run as humanly possible.
All the legal advocacy and other lawyer-involved activities are done pro-bono, which is lawyerspeak for donated time and skills. They are volunteers same as everyone else who helps the OTW and AO3 to run.
If you look at the 2022 budget, Legal Advocacy gets $4,000 to spend on 'filing fees and other costs associated with conferences and hearings'. Their budget is mostly to cover the price of paperwork.
Misconception: Collections exist for readers to organize works.
Readers can organize works through collections, but this feature wasn't built to be reader-focused. The function is primarily intended for zine, challenge, and other fannish community event organizers. The collection page layout is structured the way it is because collection pages were supposed to help event organizers relay information about an event before it starts and help event participants sort works after an event has completed.
For people who do use collections to organize things they have read, you can create collections of your bookmarks.
Misconception: The Anonymous collection is run by AO3.
None of the anonymous collections on AO3 are officially maintained by AO3 volunteers. They're collections that belong to individual people and function the same way any other collection would.