Impact printers physically strike paper to print, using electromagnets to move print pins that transfer ink from a ribbon to the paper. The three main types are dot matrix printers, which print one character at a time; daisy wheel printers, which rotate a character wheel; and line printers, which print an entire line at once. Barcode scanners illuminate barcodes with LEDs or lasers, use sensors to read the light reflection pattern, convert it to digital data, and decode it into text sent to a computer. Common illumination methods include single-point LEDs in wands/slots, linear LED arrays, and lasers that can scan from inches to feet away.