Elasticity is the ability of something to stretch and then return to its original shape. A rubber band has high elasticity: you can pull it to twice its length, and when you let go, it snaps right back. A piece of clay has no elasticity: once you stretch it, it stays stretched.

The word comes from elastic, which describes materials that bounce back after being stretched, squeezed, or bent. Your skin has elasticity, which is why you can make a silly face and your features return to normal. A trampoline's elasticity lets you bounce high into the air.

In economics, elasticity describes how much people's buying habits change when prices change. If the price of bubble gum doubles, kids might stop buying it entirely: that's high elasticity. But if the price of medicine doubles, sick people still need to buy it: that's low elasticity. Understanding elasticity helps businesses decide what to charge and helps economists predict how people will respond to price changes.

Scientists measure elasticity to understand everything from how bridges handle wind to how blood vessels work in your body. Materials with good elasticity can absorb shocks and impacts without breaking, which is why football helmets and running shoes use elastic materials to protect players and runners.