What are gadgets or gizmos?

A gadget is a small technological object (such as a device or an appliance) that has a particular function, but is often thought of as a novelty. Gadgets are invariably considered to be more unusually or cleverly designed than normal technology at the time of their invention. Gadgets are sometimes also referred to as gizmos.

The origins of the word "gadget" trace back to the 1800s. According to the Oxford English Dictionary, there is anecdotal evidence for the use of "gadget" as a placeholder name for a technical item whose precise name one can't remember since the 1850s; with Robert Brown's 1886 book Spunyarn and Spindrift, A sailor boy’s log of a voyage out and home in a China tea-clipper containing the earliest known usage in print. The etymology of the word is disputed. A widely circulated story holds that the word gadget was "invented" when Gaget, Gauthier & Cie, the company behind the repoussé construction of the Statue of Liberty (1886), made a small-scale version of the monument and named it after their firm; however this contradicts the evidence that the word was already used before in nautical circles, and the fact that it did not become popular until after World War I. Other sources cite a derivation from the French gâchette which has been applied to various pieces of a firing mechanism, or the French gagée, a small tool or accessory. The spring-clip used to hold the base of a vessel during glass-making is also known as a gadget. The first atomic bomb was nicknamed the gadget by the scientists of the Manhattan Project, tested at the Trinity site.

Different types of gadgets are:
> Mechanical Gadgets
> Electronic Gadgets
> Programmable Gadgets
> Application Gadgets

Well, I will explain each of them in my further posts.