File used by AutoCAD, a CAD program used for 2D and 3D drawing; contains plot styles, or mappings of colors and line weights to drawing objects; stores properties such as color, dither, grayscale, pen number, line weight, fill style, and line start and end styles; used to attach reusable display properties to design objects.

STB files were developed to abstract plot styles from color-based layer styles to object-based property styles, which allows greater flexibility and portability of designs. Color-based styles are defined by .CTB files, and cannot be mixed with STB files in AutoCAD projects. CTB files may be converted to STB files using AutoCAD.