Citizens of Australia, Western European and most American countries are not required visa to enter Peru. Citizens of Bolivia, Ecuador and Chile do not require passports or visa to visit certain regions of Peru. Contact the Peruvian diplomatic representative in your country for further information.
If the purpose of your visit is tourism, the maximum length of your stay will be 90 days (you can apply for extensions with the Peruvian immigration authority). 
All travelers must carry a valid passport, or a safe-conduct issued by the Peruvian immigration authority.