Rubbers and polymers are used in many more ways than you can imagine, and in a rainbow of customized formulations. Most rubbers are synthetics, made from fairly toxic chemicals. Some retain toxicity even after curing, but others, like neoprene, become non-toxic upon polymerization, and may be used safely against the skin (as in wetsuits).
Latex is unlike any other rubber. Latex is unique since it is a natural polymer derived from tree sap. As a natural polymer, it uses water as its base solvent. It is one of the few rubber compounds that is non-toxic in a liquid and solid state. Latex has the best memory of any rubber, that is, the ability to return to its original shape
without permanent distortion. Latex is also the most sensitive of rubbers, being readily damaged by oils of any kind, by ozone, and UV light.
Latex is the stretchiest rubber, easily stretching form 400 to 1000% of its resting length. It can also be remarkably strong than most, even when quite thin. Latex is easily colored, and is naturally translucent (except when colored black or white). This translucency has been a major factor in using latex compounds as an art medium. Another important factor is that latex shrinks 3-4% when it cures. That shrinkage has to be taken into account when sizing anything made from latex. When it cures, the latex
molecules polymerize by forming bonds between sulfur molecules. These bonds continue to form over several months, progressively hardening the latex.