August 1st is the first day seniors can access the Common Application. You can use the common app to apply to over 700 schools, including University of Idaho and Stanford University. The Common App streamlines the application process, because you can send your basic information to each school on your list (though most have supplements and require additional essays and information). You should find out if the schools on your list accept the Common Application, and if so, you should take some time exploring it. Some schools do not accept the Common Application. The University of California Schools all use a single application, which also went online August 1 and which should be submitted between November 1 and 30.
And this year there is a new application used by a consortium of schools called the Coalition Application. It is interesting because it allows you to collect and share a lot more information about yourself in a portfolio, and you can start building your portfolio early in your high school years. The Coalition Application is brand new, and most schools that accept it also accept the Common Application. So why waste your time looking at it? Two reasons: first, you may find that the portfolio format gives you a better opportunity to show your strengths; second, if you are applying to the University of Washington/Seattle, there is a possibility that they will require the Coalition App. (We'll know for sure October 1 when they release their app for next year.)
If this seems complicated, I am afraid it is. If you have questions let me know and we can try to answer them together!