Morse code is a method for transmitting telegraphic information, using standardized sequences of short and long elements to represent the letters, numerals, punctuation and special characters of a message. The short and long elements can be formed by sounds, marks or pulses, in on off keying and are commonly known as "dots" and "dashes" or "dits" and "dahs". If you need a list of the alphabet in Morse code please click on the image to the left.
SOS actually did not stand for anything, orginally; "Save Our Seamen", "Save our Ship", "Survivors On Shore", "Save Our Souls" or "Save Our Selves" are just ways to guess the meaning. But in reality, it was used because the letter S and O are easy to make and are distinctive. The letter S has a distinctive 3 dots (...) and the letter O has a distinctive 3 dashes (---). Click on the image above for a list of the rest of the Alphabet in Morse Code.
International Morse code is composed of six elements:
These six elements serve as the basis for International Morse code and therefore can be applied to the use of Morse code world-wide.
Morse code can be transmitted in a number of ways: originally as electrical pulses along a telegraph wire, but also as an audio tone, as a radio signal with short and long pulses or tones, or as a mechanical or visual signal (e.g. a flashing light) using devices like an Aldis lamp or a heliograph. Morse code is transmitted using just two states — on and off — so it was an early form of a digital code. However, it is technically not binary, as the pause lengths are required to decode the information.
Originally created for Samuel F. B. Morse's electric telegraph in the early 1840s, Morse code was also extensively used for early radio communication beginning in the 1890s. For the first half of the twentieth century, the majority of high-speed international communication was conducted in Morse code, using telegraph lines, undersea cables, and radio circuits. However, the variable length of the Morse characters made it hard to adapt to automated circuits, so for most electronic communication it has been replaced by more machinable formats, such as Baudot code and ASCII.
The most popular current use of Morse code is by amateur radio operators. Although no longer a requirement for Amateur licensing in most countries, it also continues to be used for specialized purposes, including identification of navigational radio beacon and land mobile transmitters, plus some military communication, including flashing-light semaphore communications between ships in some naval services. Morse code is the only digital modulation mode designed to be easily read by humans without a computer, making it appropriate for sending automated digital data in voice channels, as well as making it ideal for emergency signaling, such as by way of improvised energy sources that can be easily "keyed" such as by supplying and removing electric power (e.g. by switching a breaker on and off).