The document describes the steps to create a barcode brush in Photoshop: 1) A 1px wide by 100px tall document was made and filled with black to create a brush preset. 2) The brush preset was used to create a new barcode by selecting the brush tool and drawing vertical lines while holding shift. 3) Additional settings were applied to the brush like 130% spacing and 0% scatter with 100% count jitter to generate the barcode pattern.