Wikipedia:Categories versus lists
Categories are decentralized, and were implemented this way for ease of indexing pages during page creation, and to split up the work of category maintenance between page maintainers.
This is an essay on categories, lists, and series boxes.
It contains the advice or opinions of one or more Wikipedia contributors. This page is not an encyclopedia article, nor is it one of Wikipedia's policies or guidelines, as it has not been thoroughly vetted by the community. Some essays represent widespread norms; others only represent minority viewpoints.
But the category system causes more problems than it solves:
- Pages are synonymous with hangouts. Editors have their favorite pages that they watch over and maintain. This includes maintaining the category tags on those pages. Each editor's views on categorization differ. So when you decide to add a large group of pages to a category, some of the watchdogs are bound to object to and remove that tag from their pages. This punches holes in the categories which can lead to edit wars when you try to fill those holes. By contrast, lists are centralized, so you usually don't have to worry about the watchdogs, because you link to their pages without altering their pages at all. In most cases, they won't even be aware of the link.
- Categories don't have page histories. When a category tag is removed from a page, and the link to that page disappears from the category page, there is no record at the category page of that link ever being there. So the only ways to spot link disappearances is either from memory, or cross-checking against a list of what was there, or seeing the category on the watchlist, the last option is a setting at "watchlist". Lists have histories, so by using diff, you easily monitor for deletions.
- When a category is deleted, it can't be undeleted and restored. All the tags leading to it will have been removed. The information contained in the tags cannot be rebuilt as easily as a page can. It would require going through the page history of all of Wikipedia to refind the deleted tags.
- When a page is deleted, it disappears off the category system, and most people aren't likely to notice unless they are specifically looking for it (but they usually use search when they look for specific topics), so this could hurt readers who are forced browse incomplete categories. With lists, when a page linked to is deleted, the link turns red. If the article was important, those who monitor the list are alerted to the problem and can take measures to repair the damage done to the subject area.
- Categories can't include page names that don't exist yet. Lists can. Redlinks are useful as gap indicators and as task reminders (to create those articles).
- Because of the category system's decentralized nature, adding or subtracting links is cumbersome and requires going to each page. This slows down category filling and category trimming, and can disrupt the brainstorming process that some editors use to create lists. Lists on the other hand can be built rapidly using cut & paste and text editing on the spot. Glossaries on the web can be captured and trimmed down to just the terms, then sorted using a command or program, then a macro applied to format them into links, and then pasted onto a Wikipedia page. Vocabulary and term lists are even easier to convert into Wikipedia lists. It's amazing how many of the links turn blue – Wikipedia's coverage is extensive, but pages often remain undetected or buried somewhere in an obscure category until a good list is made.
- Categories aren't modular, lists are. So new lists can be created from parts of other lists, and subsections of lists turned into new pages when the list grows too large.
Likewise, categories can have advantages over lists: