Rubber can be natural or synthetic. Natural rubber comes from latex extracted from plants like rubber trees. It is stretchy and flexible. Synthetic rubber is man-made using a polymerization process and common types include polybutadiene and styrene-butadiene. Vulcanization is a process that converts natural or synthetic rubber into a more durable material by adding sulfur or other compounds, which causes cross-linking between polymer chains. This makes the rubber stronger and able to withstand a wider range of temperatures compared to natural rubber.