Printing plates question

[Daniel van Eijmeren]

After having sent my previous email, I realize I forgot to ask 
some questions of my own:

What exactly are printing plates?
And are they from a certain period, or are they still used today?

I remember having seen gold-coloured plates for newspapers, which 
looked like a giant stamp, containing a relief with a mirrored 
picture of what has to be printed on paper. Is that a printing 
plate?


Best wishes,

--- Daniël

"Ouch! More automation!"
(Which Barks story?)