Contrary to common belief, categories and tags are not the same. I know a lot of people believe that, or use them in a redundant way. But the reason why both exist is, there is always a logical way to get somewhere and an intuitive way.

Categories:
Separation of information into groups and sub groups, creating a taxonomy tree that follows a certain category pattern

Tags:
Keywords associated with a certain topic, based on (relatively) free association chains

Let’s assume that an advertising agency created an ad campaign for its client, an italian pasta company. The campaign consists of ads in TV, radio, the web, print (magazines and daily press), billboards etc. So it’s a full blown advertising campaign, using all sorts of media. I saw an ad on TV and want to look it up on the advertising agency’s website. By clicking on a certain category name, like media, I am presented a list in categorical order.

Main category
Media

Sub category
Billboard, TV Commercial, Newspaper Ad, Magazine Ad, Web Ad (sub categories)

Alternatively, browsing through the same web site, something is catching my attention. I was not looking for wine, but wine is somehing I might enjoy with a dish of italian pasta. Maybe I was not looking for it, but all of a sudden I found this great ad campaign for italian wine. That way I might get from pasta, to wine, to opera and beyond.

Tags
pasta, italian life, lifestyle, way of life, amore, linguini, tomato sauce, basil, italian wine, montepulcano, opera …

Creating as many tags as possible to broaden the association chain does not help sorting things out. Hundreds of partially redundant tags have a tendency to confuse a matter. I see this happening on social bookmarking sites like Ma.gnolia, where the bookmark for Flickr, which I tagged with “folksonomy, photo” is tagged with “blogs, web 2, web design, pictures, grandma, fun, gallery, hype, photoshop” and so on by other people.

If applied carefully, tags can enhance the browsing experience. Tags let people dive intuitively through the information architecture of a website. Of course tags could as well be left away entirely. But their functionality is not necessarily redundant with the use of categories.

One way of going through a website is using your logics, another way is using your intuition. In real life, we do this a lot. Take a simple walk to a clothing store. Maybe you are entering the store with the idea to buy a pair of jeans. Chances are, you will leave the store with a pair of jeans, and a jacket, some socks, briefs, or two plain t-shirts. Why? Because you were surrounded with offerings that were not sorted by category but by association. You were allured by visual suggestions. That is the same like tags can work on a web site. They can draw you into something. Not because you were looking for it, but maybe out of curiosity.

Tags are a powerful feature. I know many people in the blogosphere use them as a category replacement. It’s not wrong, it might work well for them. However, using tags as an element for intuitive navigation has the power to add a lot of user driven dynamics to your information architecture. Applied carefully, tags will not only help you to find stuff (like categories do), they also have the power to make you stay a little longer, because you find awesome stuff you never knew you were looking for.