To travel abroad to almost any other country (including, effective 2007, Canada and Mexico) you will need a passport. You will need to apply for a new passport if you have never had one before, if your passport was issued before your 16th birthday, or if you passport is more than 15 years old. You passport must be valid 6 months from your expected date of return. You can apply for a new passport.
If you already have a passport and that passport is your most recent one, it was issued within the past 15 years, and you were over age 16 when it was issued, you may renew your passport by mail.
To do this:
A visa is a sticker, stamp or piece of paper attached to your passport that allows you to travel to a country for a certain period of time for specific purposes (e.g., tourism, business, studies). For most countries you will need a visa if you will be staying over 90 days. However, you should confirm this with your program director or the nearest embassy or consulate of the country you will be visiting. In some cases, your program director will take care of visa arrangements. If this is not the case, you will need to do this yourself through the embassy or consulate nearest you.