There are a number of materials that tarps can be manufactured from. The tarp owes some of its ubiquity to the fact that the words refers to a wide variety of products. What materials can a tarp be made from, exactly?
Many canvas tarps are made from natural cotton fibers. The material is usually treated with wax- or oil-based water resistance treatment. These tarps tend to expand and contract a bit with the weather. Cotton is a breathable material, which can be beneficial. However, the greatest drawback is that it is not fully waterproof, just water resistant.
Cotton-based tarps are available in a number of different colors. For some tarps, the dye that gives the tarp its color is part of this process. For others, the fabric is dyed first then treated.
Some canvas tarps are made from polyester instead. In many ways, these perform similarly to the cotton-based canvas. But the synthetic material is less prone to expanding and contracting with the weather.
The most common plastic tarp is one made with polyethylene. Poly tarps are made by weaving an inner material -- called the scrim -- from higher density material (HDPE), then coating both sides of the scrim with lower density material (LDPE). The coating is typically the only part of the tarp that has pigments to give the tarp its color. PE material is fully waterproof, and it can be made in a wide range of thicknesses and strengths.
Commonly known as vinyl, polyvinyl chloride (PVC) is used primarily as a coating on a scrim made from another material, such as polyester or polyethylene. Vinyl tends to be quite strong and durable compared to other materials.
Similar to vinyl tarps, polyurethane is used as a coating on a scrim made from another material, typically polyester or polyethylene.