The Common Application and Harvard Application Supplement are the first steps on the admissions gauntlet your about to embark on.
The common application is an undergraduate application form that is accepted by over 400 schools. The application is put out by a non-profit company that is overseen by a board of directors. There is a transfer and freshman common application. It can be completed online or sent in via mail.
The common application is accepted only at institutions that accept students based on a holistic admissions model, where things such as admissions essays and letters of recommendations are used to evaluate students along with objective data like grades and standardized test scores. Harvard accepts the common application as part of their admissions package.
Of the 400+ schools that accept the common application only around 60 of them are public institutions. The use of the common application varies by institution. Some schools use the common application as its only form of application while others require the common application along with other forms.
Filling out the online common application saves a lot of time because much of it you only have to fill out once, even when applying to multiple schools. It also allows you to upload essays and track the status of your application at the schools you applied to. The common application can be found at: www.commonapp.org
Harvard Application Supplement
The Harvard Application Supplement can be filled out online at the same time you complete the Common Application. The Supplement can be printed and mailed if you prefer.
Standard information is requested on the Supplement, such as name and address, as well as the fields of study you are most likely to pursue and activities of interest. At this time, you may submit additional materials, such as a supplemental essay.