Letterpress was used in everyday printing technique for 5th centuries, until offset lithography took over.
The inks applied to the surface of metal type, which has a raid surface with a reverse image, like a rubber stamp and the type is pressed against paper to make an impression.
The final outcome, finished article would have a tactile quality, with a thick layer of ink and a slight indention where the type pressed against the paper. Images would use the same process to produce in a similar way, using blocks of wood, metal, lino or nylon.
I find letterpress printing extremely time consuming and labor intensive and in age of lithography and digital printing it might seem like wasted effort. It isn’t an alternative to modern, commercial printing techniques but it retains its place as craft ideally suited to producing beautiful unique things in small qualities.
To want a good quality outcome when using letterpress, the person would required a incredible amount of skills needs to be put in. When letterpress was the main player in commercial printing, there were specialists who lined up the type (compositors) and there were the machine room staff who operated the presses. An apprenticeship took six years.
These days letterpress is usually done by one person working alone and they will have had to learn all the disciplines involved.