Application of springs
Compression spring: designed to operate with a compressive load and found in shock absorbers, spring mattresses, mechanical pencils, and retractable pens.
Extension spring: designed to operate with a tensile load. An archetypical example is a Slinky, but these are also found in luggage scales and garage door mechanisms.
Torsion spring: designed to operate with torque (twisting force); powers every clothespin and mouse trap.