The timekeeping element in every modern clock is a harmonic oscillator, a physical object (resonator) that vibrates or oscillates at a particular frequency. This object can be a pendulum, a tuning fork, a quartz crystal, or the vibration of electrons in atoms as they emit microwaves.

Stickers are very widely used when an object requires identification with a word or idea. Brand stickers may be attached to products to label these products as coming from a certain company. They may also be used to describe characteristics of the products that would not be obvious from simple examination, or to clarify either a printing error or change in the product of some kind, such as the country of origination, shift in a product’s ingredients, a shelf life date, without having to scrap pre-existing packaging for such a small change.