There are 3 main criteria for an artwork to be labelled as a creation:
- Something made from the scratch.
- General things about creating things, and its related activity.
- Things that are fiction.
In pixiv and the Doujin industry, Creation is generally defined as something that is created from the state of nothing to something without based on any existing materials. In other words, all forms of personal, original characters, literature, artwork, setting (and more) falls into this particular category. This is done to ensure that no forms of derivative elements are included in their submission. This also applies to all forms of genre as well.
The usage of this tag is almost similar to Original. In case where an artwork is tagged with both original and creation, users MAY remove one of them in order to avoid any repetitive tags. Since both of them are similar in the way they are used, the usage criteria is completely up to the original submitter.
How to Search
It is recommended to use "Exact match" option to look for creation (創作) related works due to the fact that such tag MAY clashed with the "Derivative Work" (二次創作) tag. You may even try inserting "創作 -二次創作" tag into your search field without the "derivative work" tag included.