Offset printing is a process with almost flat printing plates with both printed and blank elements at the same level. Before ink transmission the printing plates are covered with fountain solution (water based). Printing design elements attract ink and the non-printing elements attract water. The image is transffered to offset roller with rubber blanket which carries the ink to the material.
Advantages of offset printing are: deep standartisation of all processes, low cost of printing plates, low ink consumption and opportunity to print gradients from 0% to 100%.