boxdrawing

Box drawing is a set of characters used to render boxes, borders, and diagrams in text-based interfaces. It encompasses ASCII approximations and, more commonly today, the Unicode box-drawing repertoire that enables precise line art in monospaced text. In early computing, people drew frames with plus signs, hyphens, and vertical bars; these characters could produce recognizable borders but were limited in thickness and style. Unicode expanded this approach with a dedicated Box Drawing block that provides a range of horizontal and vertical lines, corners, tees, and crosses that can be combined to form panels, tables, and diagrams.

The Unicode box-drawing block spans roughly from U+2500 to U+257F, with both single-line and double-line variants. Common examples include horizontal and vertical lines, corners for the four corners, and junctions and crosses that join lines at right angles. Double-line variants exist for more decorative borders, using a separate set of box-drawing characters. The characters are designed to render in monospaced fonts and many terminals, though rendering can vary by font and platform.

Usage and compatibility: Box drawing is widely used in text user interfaces (TUIs), terminal menus, bordered panels, and diagrams in documentation and source code. In addition to Unicode, legacy code pages such as CP437 and CP850 provided box-drawing glyphs on older systems. Modern environments generally support the Unicode box-drawing block, but appearance depends on font support and rendering rules. See also: Unicode, ASCII art, text user interface.