Compression Springs are the most common. If you had a pogo stick that had a compression spring. They can be fitted on vehicles and bikes to absorb shocks. The spring can compress and then expand back to its original size. Compression springs come in a variety of sizes from very small to large. The wire they are made from can between .25mm to 19mm.
Extension Springs – extend when a weight / force is applied. To make these springs work they are supplied with a variety of endings such as loops, hooks.
Torsion Springs – these are often seen on gates to help the door close. Less visible they are also found in windup clocks and watches.