This shouldn’t be so hard to understand:
Tags are not categories.
Enough has been said about this already — I hate to be a semantics-fiend, and I dislike discussing things like tags with my hat on, all serious, but this one is clutching me by the throat.
Now the fact that wp.com reads the categories a post is assigned to as “tags” and tell technorati, ice-rocket and whoever else is listening that the tags for the post are the categories I put it in, it is terrible to think that I don’t really have tags. I would have “tagged” this very post with “tags” if I had real tags. I am not going to create a new category just so I can tag this post “tags” — kosher??
So categories can be tags but tags cannot be categories. Categories are like the huge signs you see on aisles in supermarkets – “Food”, “Hygiene”, “Frozen” etc, they guide you to sections where you can find what you are looking for. Tags are like the labels on the products themselves.
Categories organize, hierarchically. Tags need not. Tags provide meta-information, Categories need not. Tags cross-connect, Categories do not. By cross connect, I mean, when you go looking for posts tagged with “Flickr” on technorati, you find posts from various sources, all about Flickr. Now if you go searching for posts tagged with “administration” in technorati, you will find everything from system administration tips to posts regarding the NASA, the NSA, and general verbiage – largely due to poisoning from people who can’t get the difference between tags and categories straight, for the most.
Get your semantics right, wordpress.com folks – please 
If you don’t you are doing a disservice by poisoning so many indices that work by means of tags. Earlier today, for the nth time, I ended up with a wordpress.com blog as the result, and the entry was totally unrelated to what I was searching for on IceRocket.
And technorati, shame on you for saying
“A tag is like a subject or category. “
If I were in the business of earning my subsistence from the concept of tagging, I would try hard to make a distinction between the old and the new that I am offering, and to elucidate the advantages and novel uses of tags.
I would say the difference is in how people use them, not how we should control them.
Matt,
You have a point there, but I beleive that there are uses for both tags and categories on a WordPress blog. So it would be nice to be able to ascribe both categories and tags to posts at wordpress.com, for example. Now it seems like you have to choose one method over the other. Also, adding categories on the fly is MUCH improved in the new administration interface, but it is not trivially simple to add a whole bunch of “tags” to a post, some of which exist and some dont.
In an ideal world, somewhere in every visible post, on the blog itself, there is a field only the author can see where he/she can type in tags, and save on the fly – sort of like it is on flickr, if you see what I mean.
So – when an author writes a post, he puts in some categories, and types in tags in a seperate entry field, and the author has an easy way to update or add tags when he/she is reading the blog.
[...] [1] On a related topic, you might want to read Carthik’s excellent post, Tags are not Categories. [...]
Thanks Carthik for bringing this issue into the bright light of your arguments! You are absolutely right.
Categories tells us to which domain this class of posts belong.
Tags signals what matters this special post discusses, and might very well cross domains.
Categories and tags are complimentary markup systems for finding articles of interest and should be kept in separate spaces.
If they are not, tagging will be rendered unusable.
[...] I’ll leave the answer to these and other cruical questions to the more experienced bloggers and taggers, and give you some links. I recommend you first to read Carthik Sharma’s article “Tags are not Categories“, where he makes it chrystal clear, why you should not confuse one for the other. It’s good reading and will set you firmly on track. [...]
[...] Tags are Not Categories by Carthik Sharma agrees with my opinion that categories are not the same as tags, and he makes a good point. Categories organize, hierarchically. Tags need not. Tags provide meta-information, Categories need not. Tags cross-connect, Categories do not. By cross connect, I mean, when you go looking for posts tagged with “Flickr” on technorati, you find posts from various sources, all about Flickr. Now if you go searching for posts tagged with “administration” in technorati, you will find everything from system administration tips to posts regarding the NASA, the NSA, and general verbiage – largely due to poisoning from people who can’t get the difference between tags and categories straight, for the most. [...]
Excellent post, and I agree with you. I liked having LivePress automatically tag my LiveJournal posts with whatever categories I had chosen for my WordPress posts, but beyond that the two do not mix well.
I am a newbie who had a referral from a lovable geek to your site to help me understand the differences between tags and categories. Thank you for your clear writing and thanks also to those who commented before me. I was lost in a cloud tag and you became the cyberlites that shone through the darkness.
[...] Carthik Sharma » Tags are not Categories Good explanation. I still don’t want to use tags, though. [...]
Sometimes I felt tags were just invented so that a particular “keyword” could be placed near the URL so that a Crawler could rate that URL higher for the near proximity of the “keyword”
I still somewhat allow that thought of mine to stay, as it generally DOES show in the search results.
Apart from that, a tag is just a “lazy sticker to the product”
[...] So it turns out that tags are not categories. Who’d have thunk it? [...]
[...] Tagging is an essential way to add semantic information to help people find similar posts. They aren’t the same as categories, although you can use the same tools to do both. Each post should have multiple tags. Tagging is like putting a Post-It note on your favorite socks to remind you that they have pictures of Superman, so that you’d be able to find them if you couldn’t see the sock but you could still see the Post-It. That’s a really bad analogy. [...]
Belated related: http://climbtothestars.org/archives/2006/02/11/tags-and-categories-are-not-the-same/
Tags are in Categories are out?
For decades the Internet has tried to structure the navigation for a user using the concept of categories.
[...] Wordpress allows you to categorize your blog posts. There are also some plugins that let you work with tags. Seemingly both of them can be used for the same thing – qualify your posts. However, I think they are different, or at least my usage is different. On this blog I use categories for topics and tags for keywords. Both can be used for navigation, but categories present structured navigation, its language is specific to this blog. The keywords are global, which would stand their context and meaning even outside this blog. Posts by Carthick Sharma and Lorelle give the best explanation. [...]
[...] Tags are NOT categories -Crits to Wordpress.com- Carthik Sharma, in the Tags are Not Categories article, points out a very frustrating Wordpress.com confusion, stating loud and clear that categories are not the same with tags, and he’s got a good point. Categories organize, hierarchically. Tags need not. Tags provide meta-information, Categories need not. Tags cross-connect, Categories do not. By cross connect, I mean, when you go looking for posts tagged with “Flickr? on technorati, you find posts from various sources, all about Flickr. Now if you go searching for posts tagged with “administration? in technorati, you will find everything from system administration tips to posts regarding the NASA, the NSA, and general verbiage – largely due to poisoning from people who can’t get the difference between tags and categories straight, for the most. [...]
Just used the export / import function from WP to get my postings to another domain my mine. Everything went all right ‘cept the tags. All my tags were shown as categories and that was really confusing. I immediately dumped the database and now will ask my brother to do everything manually for me. Trying to find something about this issue I stumbled upon your site. Your posting is more than a year old but you are still right. I don’t understand why WP is so eager to play around with tags. Their category system was perfect. Also, now links are seen as categories. It’s all really confusing.
[...] flexibility for organising categories and tags. Going through the discussions on categories vs tags from the Wordpress community is refreshing to see usage disparities. Flexibility is needed. [...]
[...] I was really disappointed when WordPress.com started confusing categories for tags, and wrote about why Tags are not Categories. WordPress has finally come clean, and seen the light, and explained what’s what over at the [...]
[...] Tags: Uncategorized Wed, Sep 26, 2007 8:45 pm Garrick Van Buren Information Architecture “Categories organize, hierarchically. Tags need not. Tags provide meta-information, Categories… [...]
[...] Source: Carthik Sharma [...]
Again another newb thanking you for the clear and precise explanation.
[...] Tags are Not Categories [...]
[...] post editor that merges raw .html editing with the rich-text interface, as well as support for tags, ala slashdot. The admin screen also lets you know when a given plugin has an upgrade available. [...]
[...] Carthik Sharma » Tags are not Categories [...]
[...] to use as a tag, and which category describes it best… Taking advice from Carthik Sharma – Tags are not Categories. Though, knowing me, it’ll take a while for those to get cleaned [...]
[...] think of categories as a table of contents and tags as the index page of a book.” Or as Carthik Sharma said, “Categories are like the huge signs you see on aisles in supermarkets – ‘Food’, [...]
[...] Excerpt from post at http://carthik.net/blog/vault/2006/02/21/tags-are-not-categories/ [...]