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Tag cloud
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A tag cloud or word cloud (or weighted list in visual design) is a visual depiction of user-generated tags, or simply the word content of a site, used typically to describe the content of web sites. Tags are usually single words and are typically listed alphabetically, and the importance of a tag is shown with font size or color. Thus both finding a tag by alphabet and by popularity is possible.
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Encyclopedia
A tag cloud or word cloud (or weighted list in visual design) is a visual depiction of user-generated tags, or simply the word content of a site, used typically to describe the content of web sites. Tags are usually single words and are typically listed alphabetically, and the importance of a tag is shown with font size or color. Thus both finding a tag by alphabet and by popularity is possible. The tags are usually hyperlinks that lead to a collection of items that are associated with a tag.
Definition
A tag cloud is a set of related tags with corresponding weights. Typical tag clouds have between 30 and 150 tags. The weights are represented using font sizes or other visual clues. Meanwhile, histograms or pie charts are most commonly used to represent approximately a dozen different weights. Hence, tag clouds can represent many more weights, though less accurately so. Also, frequently, tag clouds are interactive: tags are hyperlinks typically allowing the user to drill down on the data.
History
The first use of tag clouds on a high-profile website was on the photo sharing site Flickr, created by Flickr co-founder and interaction designer Stewart Butterfield. That implementation was based on Jim Flanagan's Search Referral Zeitgeist, a visualization of Web site referrers. Tag clouds have also been popularized by Del.icio.us and Technorati, among others.
The first published appearance of a tag cloud (or at least a weighted list) can be attributed to the "subconscious files" in Douglas Coupland's Microserfs (1995).
Prior to weighted list representation of tag clouds, paper maps had used the concept of weighted font size and font weights to represent relative size or importance of towns and cities.
Types
There are three main types of tag cloud applications in social software, distinguished by their meaning rather than appearance. In the first type, there is a tag cloud for each item whereas in the second type, we have global tag clouds where the frequencies are aggregated over all items and users.
In the first type, size represents the number of times that tag has been applied to a single item. This is useful as a means of displaying metadata about an item that has been democratically 'voted' on and where precise results are not desired. Examples of such use include Last.fm (to indicate genres attributed to bands) and LibraryThing (to indicate tags attributed to a book).
In the second, more commonly used type, size represents the number of items to which a tag has been applied, as a presentation of each tag's popularity. Examples of this type of tag cloud are used on the image-hosting service Flickr and the blog aggregator Technorati.
In the third type, tags are used as a categorization method for content items. Tags are represented in a cloud where larger tags represent the quantity of content items in that category.
More generally, the same visual technique can be used to display non-tag data, as in a word cloud or a data cloud.
Visual appearance
Tag clouds are typically represented using inline HTML elements. The tags can appear in alphabetical order, in a random order, they can be sorted by weight, and so on. Some prefer to cluster the tags semantically so that similar tags will appear near each other. Heuristics can be used to reduce the size of the tag cloud whether or not the purpose is to cluster the tags.
Data clouds
A data cloud or cloud data is a data display which uses font size and/or color to indicate numerical values It is similar to a tag cloud but instead of word count, displays data such as population or stock market prices.
Text clouds
A text cloud or word cloud is a visualization of word frequency in a given text as a weighted list. The technique has recently been popularly used to visualize the topical content of political speeches.
Collocate clouds
Extending the principles of a text cloud, a collocate cloud provides a more focused view of a document or corpus. Instead of summarising an entire document, the collocate cloud examines the usage of a particular word. The resulting cloud contains the words which are often used in conjunction with the search word. These collocates are formatted to show frequency (as size) as well as collocational strength (as brightness). This provides interactive ways to browse and explore language.
See also
External links
- - an information design analysis of tag clouds
- - comparison of tag cloud visual designs
- - software development guide from O'Reilly's ONLamp
- - Learn how to develop a tag cloud using PHP
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