Offset printing is a commonly used printing technique where the inked image is transferred (or "offset") from a plate to a rubber blanket, then to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique employs a flat (planographic) image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a water-based film (called "fountain solution"), keeping the non-printing areas ink-free.

Ira Washington Rubel invented the first offset printing press in 1903.

Offset printing is the most common form of high-volume commercial printing, due to advantages in quality and efficiency in high-volume jobs. The more you print, the less you pay per page, because most of the price goes into the preparation undergone before the first sheet of paper is printed and ready for distribution. Any additional paper print will only cost the client paper price (and ink), which is very minimal. While modern digital presses (Xerox iGen3 Digital Production Press or the family of HP Indigo solutions or Kodak Nexpress solutions, for example) are getting closer to the cost/benefit of offset for high-quality work, they have not yet been able to compete with the sheer volume of product that an offset press can produce. Furthermore, many modern offset presses are using computer to plate systems as opposed to the older computer to film workflows, which further increases their quality.
In the last two decades, flexography has become the dominant form of printing in packaging due to lower quality expectations and the significantly lower costs in comparison to other forms of printing.

Offset printing advantages

Advantages of offset printing compared to other printing methods include:

• Consistent high image quality. Offset printing produces sharp and clean images and type more easily than letterpress printing because the rubber blanket conforms to the texture of the printing surface.

• Quick and easy production of printing plates.

• Longer printing plate life than on direct litho presses because there is no direct contact between the plate and the printing surface. Properly developed plates running in conjunction with optimized inks and fountain solution may exceed run lengths of a million impressions.

 
• Cost. Offset printing is the cheapest method to produce high quality printing in commercial printing quantities.

Offset printing disadvantages

Disadvantages of offset printing compared to other printing methods include:

• Slightly inferior image quality compared to rotogravure or photogravure printing.

• Propensity for anodized aluminum printing plates to become sensitive (due to chemical oxidation) and print in non-image/background areas when developed plates are not cared for properly.

• Time and cost associated with producing plates and printing press setup. This makes smaller quantity printing jobs impractical. As a result, smaller printing jobs are now moving to digital offset machines.