Computer printer in Wikipedia page
In computing, a printer is a peripheral device which makes a persistent human-readable representation of graphics or text on paper. The first computer printer designed was a mechanically driven apparatus by Charles Babbage for his difference engine in the 19th century; however, his mechanical printer design was not built until 2000. The first electronic printer was the EP-101, invented by Japanese company Epson and released in 1968. The first commercial printers generally used mechanisms from electric typewriters and Teletype machines. The demand for higher speed led to the development of new systems specifically for computer use. In the 1980s were daisy wheel systems similar to typewriters, line printers that produced similar output but at much higher speed, and dot matrix systems that could mix text and graphics but produced relatively low-quality output. The plotter was used for those requiring high quality line art like blueprints.
Źródło: https://en.wikipedia.org/wiki/Printer_(computing)
Not only leaflets
Printing is not only printing leaflets, business cards or large banners - it also prints other, necessary materials such as: stickers, self-adhesive letters or labels. In principle, everything that comes out of the printing house can be included in the category of printing.
There are plants specializing in the production of only a specific group of printed materials: eg leaflets, or only large-format printing. However, this results from a simple thing: for every type of printing you need to have the right machine, and these take up space and cost a lot. That is why printing plants limit the amount of services provided.
What programs dominate in printers
There are more and more graphics processing programs, from the most popular Photoshop to less known and free ones like Inkscape. Professionals usually use one or two proven programs, which translates into their high productivity.
In the work of graphics or DTP operator you usually need a program for processing vector and raster graphics. You can also include word processors, programs provided by print equipment manufacturers, to the pool of programs needed for such work.