Variable-data printing (VDP) (also known as variable-information printing (VIP) or VI) is a form of digital printing, including on-demand printing, in which elements such as text, graphics and images may be changed from one printed piece to the next, without stopping or slowing down the printing process and using information from a database or external file. For example, a set of personalized letters, each with the same basic layout, can be printed with a different name and address on each letter. Variable data printing is mainly used for direct marketing, customer relationship management, advertising, invoicing and applying addressing on selfmailers, brochures or postcard campaigns.