弹簧是一种利用弹性来工作的机械零件。一般用弹簧钢制成。利用它的弹性可以控制机件的运动、缓和冲击或震动、储蓄能量、测量力的大小等。广泛用于机器、仪表中。

弹簧的受力与变形符合虎克定律，即受力与形变量需成正比，见下式:

A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. There are a large number of spring designs; in everyday usage the term often refers to coil springs.

Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication. Some non-ferrous metals are also used including phosphor bronze and titanium for parts requiring corrosion resistance and beryllium copper for springs carrying electrical current (because of its low electrical resistance).