Sets, like pools, are groups of posts. Unlike pools, however, sets do not necessarily have a common theme.
Sets can be public or private. Public sets are visible to all users. Private sets are only visible to the owner.
Sets have a short name as well as their full name. Short names must be at least three characters long, and cannot consist only of numbers (i.e., they must have at least one letter or underscore). Short names can only contain lowercase letters, numbers, and underscores. Short names are used to search for posts in the set using the set: metatag. To view posts in a set, search for set:set_name where set_name is the short name of the set you want to search for.
Sets are not subject to the same strict moderation that pools are subject to. Pools are shown prominently at the top of a post's page, so adding posts to pools they don't belong in can be detrimental. Adding a post to a set, on the other hand, takes up no space on the post's page; therefore a post can be in many sets without any drawbacks. Obviously, creating public sets for the purpose of harassing users or spamming the set list will not be tolerated.
To add posts to a set, click Add to Set on the left side of any post, select the desired set from the dropdown and click Add. You can also select Add to set... from the Post Mode dropdown on the post index, select a set from the dropdown below it, then click any post to add it to the set. Use this same method (selecting Remove from set...) to remove posts from a set.
You could use private sets as second, third, etc. 'favorite' groups, to further organize posts. Or, as an artist, you could organize your art into separate 'folders' such as sketches, inks, commissions, etc.
Should a group of posts go into a pool or a set? If the posts naturally belong together, such as pages of a comic or a series of closely related images drawn by one artist, they should go into a pool. Posts that only belong together because of you (for example, your favorite images, or images of your various characters) should go in sets.
Admins have the ability to edit the name, short name, and description of public sets, and to make public sets private. They cannot view or edit any details about private sets, make private sets public, or add/remove posts from any set they don't own or maintain.
Transfer on Delete
If the Transfer on Delete option is enabled, then when a post is deleted from the site, its parent (if it has one) will be added to the set in its place. This emulates the behavior with favorites, where favorites are transferred to a post's parent on delete. Disable this option if you would prefer to have the post simply removed from the set with no replacement when it is deleted.
Set owners can assign users as 'maintainers' of a set, allowing them to add or remove posts from a set. Even if a private set has maintainers, they still cannot see or modify the set in any way until it is made public.
When a user is invited to maintain a set, they can approve the invitation, which makes them a maintainer, deny the invitation, or block it, which prevents them from being invited to maintain that set again in the future. To view your invites, visit this page.
When a set is made private, all maintainers are notified, and any un-accepted maintainer invites are deleted. When a set is made public again, all maintainers are notified.