What is flexo or flexography?
Flexography (aka flexo) is a printing process which utilizes a flexible relief plate. Basically it's a modern version of a letterpress which it's used to print on almost any type of material, including plastics, metallic films, cellophane, and papers.
It is mostly used for printing on the non-porous substrates. The most common use is in food packaging.
Flexographic Printing was born in England around 1980 by Bibby, Baron and Sons. Originally, flexographic printing was poor in quality. Labels requiring high quality have generally been printed using the offset process until recently
The greatest advances in flexographic printing have been in the area of photopolymer printing plates, including improvements to the plate material and the method of plate creation.
Laser-etched ceramic anilox rolls also helped a lot in the improvement of print quality. Full-color picture printing is now possible, and some of the finer presses available today, in combination with a skilled operator, allow quality that rivals the lithographic process. One ongoing improvement has been the increasing ability to reproduce highlight tonal values, thereby providing a workaround for the very high dot gain associated with flexo printing.
Via: Wikipedia