Laser engraving is probably the most permanent technique. It is about to mark an item with a laser printer. When the laser light touches the item surface, it erodes the material layers so the image can be shown. This can make color and texture changes.
It is usually used on materials such metal, glass, wood, leather and leatherette. This kind of materials are difficult to work when it comes to be printed with other techniques, so the best one is laser engraving.
In adittion to the permanent results, they will make the item become ellegant and sublime. For example, laser engraving on wood results will appear as burned wood, something special and unique, impossible to aim with other printing techniques.