According to an article by eMarketer: Making Usability a Priority for Travel Sites – “Navigability and functionality second only to price.” “Cost is a major factor for both business and leisure travelers when booking their trips, but even when the price is right, users will balk at Website problems or abandon their purchase if they have trouble navigating and dealing with the checkout process. Customers are time conscious and impatient. If they do not find what they want, within seconds, they will leave your site and go on to your competitor’s site.”
Think of a poorly designed website navigational menu as a car with a broken GPS. You may end up where you do not want to be, with the inability to find your way back. Another visual way to approach this would be to think of a store’s site maps. Imagine a department store with a site map leaving you unable to locate the product that you need.
The term usability simply means is a site easy to navigate? Are the links helpful and practical? Do they help the consumer complete a purchase, download a product, or get the information and details they need to make a better-informed decision? Or – does the site frustrate and confuse, have too many popup advertisements with flashy rollovers, inaccurate link descriptions? Do your links take too much time to activate – do they lead the consumer in the right direction?
Website navigation usability is just a portion of the website functionality challenge. Components such as ease of access, hardware and software, the homepage, page structure, scrolling, headings, hyperlinks, back-links, text, and visual appeal, are just some of the key elements that need to be taken into account when building a useful and practical website. Having said that, without having a well designed, thought out navigation system, your online visitors can become annoyed and frustrated, ultimately leaving your site, in pursuit of your competitor’s site which may be easier to navigate and understand.
http://www.usability.gov/guidelines/
http://www.smashingmagazine.com/2009/09/24/10-useful-usability-findings-and-guidelines/
http://www.netmechanic.com/news/vol7/design_no4.htm
http://www.webpagesthatsuck.com/
http://vandelaydesign.com/blog/galleries/inspirationalnavigation-menus/