There is a great history which tells everyone that we should be aware of stone age. At that time the people used to express their feelings in the form of symbols and sign language. They used to draw the figure of animals and what every they saw in the rocks.
The same theory was later was called in various names. It was the advent of human language. It was the advent of expression. To transmit the message to other people, a medium arose from the calligraphy done from those people, which were later called printing.
Screen Printing
Screen printing is a technique which can be explained in various steps. Take a print of the artwork on a tracing sheet or even positives. It starts with exposing box, fitted with tubelights inside a wooden box with glass top. Keep the tracing facing opposite direction of the glass top. Place the screen on the glass top.
When you switch on the light, the impression on the tracing sheet imprints on the screen. Fit the screen to a clamp on the printing table. Place the paper below the screen on the table. Put the required colour on the screen. With the help of squeezer wipe the colour on the screen. You will get the impression from screen to paper.
We print a wide various of printing using screen printing, which varies from small stickers to banners. We can use screen printing for printing cloth banners and also small size rate stickers, which are used in retail shops.
Letterpress Printing
In the olden days, there was a famous type of printing, which was used for bulk printing, which was widely called Letterpress printing. It was in the early 19th century that was used to print books, newspaper and others. So that the letters which got printed would be legible and readable. Nowadays this is overtaken by offset printing and is used only for punching process and print numbers on printed copies.
Offset Printing
The present trend in the printing industry is the Offset printing. It is a process which prints copies in a speed that overtakes letterpress printing by a wide margin. It is more sharper, crispier and brighter than letter press.
External References
You can get the complete detail of how printing industry went top by visiting the below given links
https://en.wikipedia.org/wiki/History_of_printing
https://en.wikipedia.org/wiki/Printing
https://www.history.com/topics/inventions/printing-press
To get more details regarding Letterpress printing, visit the websites below
https://www.britannica.com/technology/letterpress-printing
https://en.wikipedia.org/wiki/Letterpress_printing
For more details on the screen printing you can visit the below mentioned sites
https://en.wikipedia.org/wiki/Screen_printing
http://www.businessdictionary.com/definition/screen-printing.html
There are many companies which manufacture the printing machines for offset. The below links give you a fair idea of the modern printing