You need a biometric passport to go to the United States. This passport qualifies for the Visa Waiver Program for stays of less than 90 days. To do so, you will need to fill out the ESTA form online at https://esta.cbp.dhs.gov and pay an administrative fee of US$14, payable since September 2010. Be careful to fill in the form by passing only through the site previously mentioned. Finally, for any stay longer than 90 days, the visitor must be in possession of a visa. Several types of visas exist (student, work, etc.), but they are all quite difficult to obtain. More info on https://fr.usembassy.gov/fr/