To study abroad, you must have a signed, valid passport from your country of citizenship that will not expire for a minimum of 6 months after your planned return date. If you do not have a passport, or it's about to expire, make sure you apply or renew as soon as possible! US Citizens can refer to the US Department of State's website for more information regarding passports.
A student visa is official permission by a foreign government to live and study in that country. It typically comes in the form of a stamp that is inserted directly into your passport. All US passport holders are required to obtain a student visa prior to departure for semester and yearlong students. This process can take 3-4 weeks or longer to complete. During this time, the consulate will have your actual passport while your visa is processed. Traveling internationally prior to the start of your study abroad program will interfere with your visa application process. You will need a criminal record report to start the visa process. Students studying in Brazil during the summer may obtain a 90-day tourist visa upon their arrival.
Check with your home country consulate, as well as the embassy of the country in which you plan to study, regarding visa requirements. Permanent Residents of the US should check with US Immigration as leaving the country for more than one year may jeopardize permanent resident status. Tax clearance and re-entry forms may also be necessary in these cases.