What are balloons made of?

Several materials are used in the production of modern balloons.  Natural latex rubber and metalized nylon (sometimes mistakenly called "Mylar") are the most common materials.  Latex is a natural product derived from trees and is biodegradable.  The production of latex is a natural process of many plants, and tapping of the trees does not harm the tree.  Latex harvesting discourages deforestation because latex producing trees are left intact.  A tree can produce latex for up to 40 years.