Your friend has two options. He/she can apply for ETSA. A person with ETSA is not required to obtain a visa but is limited to a maximum stay of 90 days. He/she could also apply for a tourist visa. This visa can be valid for multiple years and entries. The maximum authorized stay will be 6 months at a time. Your friend cannot simply leave and come back a few days later to get another six months as that will trigger an inquiry.
Answered on Dec 29th, 2015 at 3:10 PM