Polyhierarchy is a type of information architecture structure in which a single item can belong to multiple categories. This is in contrast to a traditional hierarchy, in which each item can only belong to one category.

Polyhierarchy can be used to improve the findability of information by making it easier for users to find information that they are looking for. This is because users may have different mental models of how information is organized, and polyhierarchy can accommodate these different mental models.

For example, a website about music might have a polyhierarchical structure for its musical instrument category. A piano could be classified as a keyboard instrument, a percussion instrument, and a string instrument. This would allow users who are looking for information about pianos to find it regardless of their mental model of how musical instruments are categorized.

Polyhierarchy can also be used to improve the usability of a website or application by making it easier for users to navigate. This is because polyhierarchy can provide users with multiple paths to the same information. For example, a user who is looking for information about pianos on the website mentioned above could navigate to the page about keyboard instruments, the page about percussion instruments, or the page about string instruments.

However, polyhierarchy should be used judiciously. If used too heavily, it can make it difficult for users to understand the structure of the information and to find the information they are looking for.

Here are some additional benefits of using polyhierarchy in information architecture:

• It can be used to represent complex relationships between pieces of information. For example, a website about a company might have a polyhierarchical structure for its organizational chart. This would allow users to see how different departments and employees are related to each other.

• It can be used to support different user tasks. For example, a website about a product might have a polyhierarchical structure for its product documentation. This would allow users to find the information they need, regardless of whether they are looking for technical information, user guides, or marketing materials.

Here are some examples of websites that use polyhierarchy:

• Wikipedia: Wikipedia uses polyhierarchy to organize its articles. For example, the article about "Piano" can be found under the categories "Keyboard instruments", "Percussion instruments", and "String instruments".

• Amazon: Amazon uses polyhierarchy to organize its products. For example, the product "Yamaha P-125 Digital Piano" can be found under the categories "Keyboards", "Pianos", and "Digital pianos".

• Google Maps: Google Maps uses polyhierarchy to organize its map features. For example, the landmark "Empire State Building" can be found under the categories "Buildings", "Landmarks", and "Skyscrapers".

Here are some references and sources:

• Polyhierarchy in Information Architecture: https://www.nngroup.com/articles/polyhierarchy/

• Information Architecture: Effective Techniques For Designers: https://uxplanet.org/information-architecture-effective-techniques-for-designers-3c993956b1e1

• The Different Types of Information Architecture Structures: https://www.galaxyconsulting.net/7-blog/167-information-architecture-components-organization-systems

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