Button (control) in the context of Electrical switch

A typewriter is a mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of keys, and each one causes a different single character to be produced on paper by striking an inked ribbon selectively against the paper with a type element. Thereby, the machine produces a legible written document composed of ink and paper. By the end of the 19th century, a person who used such a device was also referred to as a typewriter.

The first commercial typewriters were introduced in 1874, but did not become common in offices in the United States until after the mid-1880s. The typewriter quickly became an indispensable tool for practically all writing other than personal handwritten correspondence. It was widely used by professional writers, in offices, in business correspondence in private homes, and by students preparing written assignments.

A doorbell is a signaling device typically placed near a door to a building's entrance. When a visitor presses a button, the bell rings inside the building, alerting the occupant to the presence of the visitor. Although the first doorbells were mechanical, activated by pulling a cord connected to a bell, modern doorbells are electric, operated by a pushbutton switch. Modern doorbells often incorporate intercoms and miniature video cameras to increase security.