Letterpress printing is a form of relief printing of text and image using a press with a "type-high bed" printing press and movable type, in which a reversed, raised surface is inked and then pressed into a sheet of paper to obtain a positive right-reading image.
It was the normal form of printing text in the west from its invention by Johannes Gutenberg in the mid-15th century until the 19th century and remained in wide use for books and other uses until the second half of the 20th century.
In addition to the direct impression of inked movable type onto paper or another receptive surface, the term Letterpress can also refer to the direct impression of inked printmaking blocks such as photo-etched zinc "cuts" (plates), linoleum blocks, wood engravings, etc., using such a press.
The following video is a handsome introduction into the process as well as the various jobs involved:
