Avoid instructions. If you stick to the formula, anyone who has used the Web for more than a few days will know what to do. Adding “Type a keyword” is like saying, “Leave a message at the beep” on your answering machine message: There was a time when it was necessary, but now it just makes you sound clueless.
Don’t make me think
Being an expert in online usability Krug gathered his experience in a wonderful book. This summary of key thoughts will help you to remember most important principles and laws.