With the announcement of the upcoming iPhone SDK, Apple also released their iPhone Human Interface Guidelines for Web Applications available both on the web and in PDF. It’s a little over 50 pages long but it’s a very quick and easy read for anyone looking to build iPhone applications with the User in mind. Most of their advice though can be applied to other systems, especially if screen real estate is at a minimum.

The document is written in such a way that someone without much technical experience would still be able understand it. Some of the guidelines I found most important were:

• Be prepared for the probability that users will not be giving their undivided attention to your content, at least not for long.
• Make sure your layout accommodates the average size of a fingertip and finding alternatives to drag-and-drop and cut, copy, and paste.
• Before you begin to work on your iPhone web application, be sure you know precisely who your users are.
• Minimize the number of controls from which users have to choose and labeling them clearly so users understand exactly what they do.
• A webpage that is cluttered with many different sizes and styles of elements, different sizes and colors of text, and gratuitous images presents an unpleasant user experience.
• When you ask for input from users, consider using lists (or pop-up menus) instead of text fields whenever possible.
• Make sure you use interactivity to get users closer to their goal and avoid interactivity that serves no functional purpose.
• Avoid technical jargon in the user interface.