For newer findings, see this year's Intranet Design Annual: the year's 10 best intranet designs.

Your intranet and your public website on the open internet are two different information spaces and should have two different user interface designs. It is tempting to try to save design resources by reusing a single design, but it is a bad idea to do so because the two types of site differ along several dimensions:

  • Users differ. Intranet users are your own employees who know a lot about the company, its organizational structure, and special terminology and circumstances. Your internet site is used by customers who will know much less about your company and also care less about it.
  • The tasks differ. The intranet is used for everyday work inside the company, including some quite complex applications; the internet site is mainly used to find out information about your products.
  • The type of information differs. The intranet will have many draft reports, project progress reports, human resource information, and other detailed information, whereas the internet site will have marketing information and customer support information.
  • The amount of information differs. Typically, an intranet has 10–100 times as many pages as the same company's public website. The difference is due to the extensive amount of work-in-progress that is documented on the intranet and the fact that many projects and departments never publish anything publicly, even though they have many internal documents.
  • Bandwidth and cross-platform needs differ. Intranets often run 100–1000 times faster than most internet users' web access which is stuck at low-band or mid-band, so it is feasible to use rich graphics and even multimedia and other advanced content on intranet pages. Also, it is sometimes possible to control which computers and software versions are supported on an intranet, meaning that designs need to be less cross-platform compatible (again allowing for more advanced page content).

Most basically, your intranet and your website are two different information spaces. They should look different in order to let employees know when they are on the internal net and when they have ventured out to the public site. Different looks will emphasize the sense of place and thus facilitate navigation. Also, making the two information spaces feel different will facilitate an understanding of when an employee is seeing information that can be freely shared with the outside and when the information is internal and confidential.

An intranet design should be much more task-oriented and less promotional than an internet design. A company should have only a single intranet design, so users have to learn it only once. Therefore it is acceptable to use a much larger number of options and features on an intranet, because users will not feel intimidated and overwhelmed as they would on the open internet, where people move rapidly between sites. (I know of a frighteningly large number of companies with multiple intranet homepages and multiple intranet styles: Step 1 is to get rid of that in favor of a unified intranet.)

An intranet will need a much stronger navigational system than an internet site because it has to encompass a larger amount of information. In particular, the intranet will need a navigation system to facilitate movement between servers, whereas a public website only needs to support within-site navigation.

Managing the Intranet

There are three ways of managing an intranet:

  1. A single, tightly managed server: only approved documents get posted, and the site has a single, well-structured information architecture and navigation system under the control of a single designer. Even though this approach maximizes usability of the information that passes the hurdles and gets posted, this is not the best way to build a corporate information infrastructure because the central choke point delays the spread of new and useful information. A totalitarian intranet will cause you to miss too many opportunities.
  2. A mini-internet: multiple servers are online but are not coordinated, complete chaos reigns, you have to use "resource discovery" methods like spiders to find out what is on your own intranet, no consistent design (everybody does their own pages), no information architecture. This approach might seem to increase opportunities for communication across the company, but in reality does not do so since people will be incapable of finding most of the information in an anarchy.
  3. Managed diversity: many servers are in use, but pages are designed according to a single set of templates and interface standards; the entire intranet follows a well-planned (and usability-tested) information infrastructure that facilitates navigation. This is my preferred approach.

Managed diversity will probably characterize many aspects of the coming network economy, but we have less experience with this approach than with more traditional top-down management.

Just one example of improved usability from taking advantage of managed diversity: an intranet search engine can take advantage of weighted keywords to increase precision. Weights are impossible on the open internet, since every site about widgets will claim to have the highest possible relevance weight for the keyword "widget." On an intranet, even a light touch of information management should ensure that authors assign weights reasonably fairly and that they use, say, a controlled vocabulary correctly to classify their pages.

Extranets: Blended Design

An extranet is a special set of pages that are made available to selected business partners such that they can directly access computational resources inside your company. Typical examples include allowing customers to check on the status of their orders (for example, When will my urgent order ship? Did you or did you not receive our payment?) and allowing approved vendors to look at requests for proposals.

The extranet is a blend of the public internet and the closed intranet and needs to be designed as such. Fundamentally, an extranet is a part of the internet since it is accessed by people in many different companies who will be using your public website but will not have access to the truly internal parts of your intranet. Therefore, the visual style and main navigation options of the extranet should be visibly similar to the design of your internet site: your business partners should feel that the two sites come from the same company. A subtle difference in the two styles (for example, complementary color tones) will help emphasize the closed and confidential nature of the extranet.

It will often be reasonable to have links from extranet pages to pages on the public website, but you should not have links that point to your private intranet, because your business partners will not be able to follow such links.

Actual use of the extranet shares many properties with intranet use: people will be using the extranet as a major part of their everyday job, so it will be possible to use specialized language and relatively complex interactions. It may even be reasonable to assume some amount of training on the part of the users, because they will be motivated to improve the efficiency of their own business by making better use of your extranet. The training needs and the complexity of your extranet can not be too demanding, however, since you normally cannot assume that extranet users are dedicated to the use of your particular design and nothing else. A typical extranet user may be a corporate purchasing agent who may need to deal with your extranet as well as the extranets of, say, 50 other companies where he or she has placed orders. Your extranet must be fairly easy to use if this purchasing agent is to remember its features and options from one visit to the next.

See our usability guidelines for intranets for more information about creating a great user experience inside your organization.