Tag Cloud
Problem summary
The user wants to browse content by popularity or most elaborate topic
Example
Usage
- Use when users of your website can add content yourself and possibly also many tags
- Use when your website has more than 10-20 different tags, each with different weight in post-count.
- Do not use to show the categories of a strict hierarchical structure
Solution
A tag cloud is a list of tags, where the font size of each tag is larger or bigger depending on its weight. Weight in tag clouds can be represented in three different ways:
- Size represents the number of times that tag has been applied to a single item. This kind of tag cloud can help define the distribution of how the item is categorized.
- Size represents the number of items to which a tag has been applied As a presentation of each tag’s popularity.
- Size represents the quantity of content items in that category Tags are used as a categorization method for content items
Source: Tag clouds at wikipedia
There are several opinions on how tags should be ordered. Examples of ways to order tags are:- Alphabetically
- Randomly
- By weight
- In clusters of semantically similar tags (similar tags appear next to eachother)
Rationale
Tag clouds helps visualize semantic fields; how some categories have greater importance than others.
More examples images of the Tag Cloud pattern

Tag cloud at Flickr.

I’d be interested in seeing some commentary about how people use this, how often they use it, what it does that other things don’t, and, particularly, how it justfies the relatively large amount of screen real estate it uses.
Personally, looking back, I just realized that I click on something in a tag cloud perhaps once per year, and usually ignore them completely.
cjs@cynic.net
Tag clouds don’t work and don’t really make sense. Why? Because there is absolutely no reason to say that a visitor is more interested in, or more likely to want to click on, or needs help finding, things that others have found interesting.
No one searches for things on Google because other people search for them.
A tag cloud would make more sense if the visual clues said something interesting (there are new items here, this is super cool, this is classic stuff, etc).
I am aware that many developers and designers want to implement tag clouds just because it is popular, but tag clouds aren’t very useful. Especially when you have a large number of tags. It looks messy, and doesn’t provide any information that can affect user’s choice.
Just imagine the Flickr example placed in sidebar width of 200px.
I prefer lists, such as Categories (with number of posts), most popular posts, most rated posts, etc.
I’ve always been a firm believer that the size of a control should be directly proportional to its intrinsic value. In order to make a tag cloud truly useful for its size – tags would have to be limited to a particular context… and cross correlated with an extensive user profile. In the end, the specificity needed to ascribe meaning and purpose to the navigation potential of a ‘cloud’ would negate its nature and scope (i.e. Stumble Upon). The best bang for the UI buck would be implementing something similar to the iTunes feature – ‘People who bought this album also bought…’ with a list of a half dozen items listed by popularity.