Usability

Definition

Usability is a qualitative attribute that assesses how easy user interfaces are to use. The word "usability" also refers to methods for improving ease-of-use during the design process. Usability consultant Jakob Nielsen and computer science professor Ben Shneiderman have written (separately) about a framework of system acceptability, where usability is a part of "usefulness" and is composed of:

• Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design?
• Efficiency: Once users have learned the design, how quickly can they perform tasks?
• Memorability: When users return to the design after a period of not using it, how easily can they re establish proficiency?
• Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
• Satisfaction: How pleasant is it to use the design?

Benefits of usability

The key benefits of usability are:

• Higher revenues through increased sales
• Increased user efficiency
• Reduced development costs
• Reduced support costs

It is important for Web Design

Usability is the most important aspect to web design. It's all very well having a beautiful looking dynamic web site, but if it takes a long time to download or is difficult to navigate, users will give up and visit someone else's site. Users want to find the information they are looking for - if they don't find it quickly, they will look elsewhere.

Remember who you're providing the site for. Don't sacrifice usability for design. A lot of what you consider to be important when regarding usability will depend on your target audience and purpose of your site. If you think about usability before embarking on a new design project, and incorporate it into the design in the development stages, it will both look good and be useable. Put your visitors first.

Navigation

Navigation is the most important aspect of a web site. It helps users find their way around, and tells them where they are and where they can go within the site. It provides a visual means for demonstrating the hierarchy of information to be found. Good navigation often reflects good site structure.

Usually found in these forms:

1. navigation panel
2. location indicator device (breadcrumbs)
3. home button
4. links
5. html title
6. site map
7. search facility
8. the 404 (and other error pages)
9. graphics as navigation and/or links

Reference: http://www.jessett.com/web_sites/usability/