Wikipedia about laser printing
Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a negatively charged cylinder called a "drum" to define a differentially charged image.1 The drum then selectively collects electrically charged powdered ink (toner), and transfers the image to paper, which is then heated in order to permanently fuse the text, imagery, or both. As with digital photocopiers, laser printers employ a xerographic printing process. However, laser printing differs from analog photocopiers in that the image is produced by the direct scanning of the medium across the printer's photoreceptor. This enables laser printing to copy images more quickly than most photocopiers.
DTP work programs
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.
Printing at printing plants and printing plants
Paints, inks, paper, toners, foils and other consumables - these are things that can not be missing from printing plants. They are ordered wholesale and also consumed in bulk. For each order, the production costs are optimized, and the appropriate technique and type of printing is selected.
Graphic designers, DTP operators and printers deal with this. They are responsible for the quality of the printout and as soon as something is wrong they are the first to be targeted by the dissatisfied boss. Their work is quite hard and I have to admit that you have to really have a fuss to do it. Work after hours, maximum focus and responsibility - definitely not work for everyone.