Simply by way of FYI, for most countries, the stamp they put in your passport during your processing at immigration *is* your tourist visa. You needn't have anything other than proper documentation of your identity, a polite attitude toward the official, and, sometimes, proof that you have a plane ticket or the like back out of the country at the end of your stay. Some countries--generally ones not on good terms with one's home government, or those who have stricter immigration policies--require that the visa be arranged in advance via consulate/embassy vetting. However, as an American, I've traveled all through North America, South America, Europe, and Australia without needing any advance work. The stamp will have an expiration date, at which point you need either to have left the country or to have arranged for a visa extension (which would be an additional stamp/document in your passport).