A "blueprint" is a detailed plan or design that outlines how something will be built or created. Originally, blueprints were copies of technical drawings that were created using a special process that turned the lines and text into a blue background with white lines. In a broader sense, the term can also refer to any comprehensive plan or strategy for achieving a particular goal.
The word "blueprint" comes from the blue printing process used in the 19th century to reproduce architectural and engineering drawings. The term combines "blue," referring to the color of the paper, and "print," which means to produce a copy of a text or image.