'Passports and Visas' are often used together, so it's no wonder there's confusion with the terminology.
You MUST have a valid Passport to travel internationally.
You MAY need a Visa when traveling to specific countries
A Passport is a government-issued identification confirming your citizenship.
Information on how to apply and/or renew your U.S. passport may be found here.
A Visa is a written, pre-approved authorization to travel to another country. Most countries do no require Americans to obtain a Visa for entry, but some do. Note that entry/exit requirements for some countries requiring a Visa may have different requirements when traveling by air vs by cruise ship.
Information on visa requirements for Americans traveling abroad may be found here. This includes entry/exit requirements for specific countries.
To obtain a Tourist Visa, please visit www.zvs.com.