Usability Rules and Principles for Web Design
1. 7 links in your navigation – George A. Miller’s studies showed that the human brian short term memory can only retain 5 – 9 things at a time. In this case it is a good practice to only have the max of 7 links in your navigation. Pretty interesting! I did not realize that until I found this information.
2. 2 second rule – This is a rule that the user should not have to wait more then 2 seconds for something to happen. Say if they click a link and a new page loads or any kind of reaction from a user action. This has always been a struggle for me. I am always trying to optimize my web site so it will load faster and response better.
3. 3 Click-Rule – This rule suggest that if a user does not find what they are looking for in 3 seconds that they will leave the site.
So here are a couple of rules to follow when designing user interfaces. There are plenty more that you can find at smashing magazine.