You will have to establish that you satisfy the requirements under U.S. law to obtain the category of visa for which you're applying. Visitors wishing to stay for over 3 months must receive a visa. The good thing is that all visa types can easily be acquired with a form that it is possible to download from the net and fill out before your departure date.
This Travel Authorization is readily available for citizens of eligible nations and who complete the on-line application practice. Applicants are therefore advised to observe the Visa Type and Requirements above and apply in advance in order to prevent any delays.