Offset is a quick-marking technique that prints on material indirectly.
This is a method to reproduce documents or images where the image is first engraved on a metal sheet. The ink goes from the metal or aluminium sheet to the blanket cylinder and then to the material, exerting pressure between the blanket cylinder and the pressure cylinder.
The main characteristic is that it prints indirectly and at a high speed. One sheet is used for each colour to be printed (just like screen printing). This way, if one wishes to print an image with many different colours, one must be created for each CMYK colour (cyan, magenta, yellow and key). Moreover, a fifth colour must be added, the colour of the media. This is normally white. This is how coloured images are printed, which in Graphic Arts is normally called four-colour or photochrome.
The results obtained from this stamping process are high-definition. This is an efficient process that can be applied to different papers: card stock, couché paper, coated paper, etc., as well as PVC and thin materials in general.
This is a more complex technology that requires programming the machine, which is what automatically prints directly.