System for representing letters, numerals, and punctuation marks by a sequence of dots, dashes, and spaces. It is transmitted as electrical pulses of varied lengths or analogous mechanical or visual signals, such as flashing lights. The original system was invented by Samuel F.B. Morse in 1838 for his telegraph; the International Morse Code, a simpler and more precise variant with codes for letters with diacritic marks, was devised in 1851. With minor changes, this code has remained in use for certain types of radiotelegraphy, including amateur radio.