Now simply called "CW", radio communication by Morse code was the only way to communicate for the first decade or more of Amateur Radio. Radiotelegraphy, the proper name, descends from landline (wired) telegraphy of the 19th century, and retains some of the old culture, including a rich set of abbreviations and procedures. Morse sent by spark gap transmitter was the first wireless communication mode. These "damped waves" were very broad and inefficient for communication. They were soon replaced by "Continuous Wave" (CW) transmission, using vacuum tube oscillators that were capable of a very pure note. Today, modern Amateur Radio transceivers use solid state components and microprocessors to support a variety of communication modes including CW, voice, image and many digital data modes.

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• A Standard for Morse Timing Using the Farnsworth Technique 
  Jon Bloom KE3Z, April 1990 QEX pp 8-9.
• The PicoKeyer--An Ultra Low Power CW Memory Keyer 
  Dale L. Botkin, N0XAS, December 2003 QST pp 38-40
• Code-Practice Oscillator (beginner)
  ARRL Now You're Talking pp. 11-1 to 11-2
  This is a complete oscillator that mounts on a small piece of wood.
  CPO Construction Steps.ppt 
  Pictures of the oscillator being assembled.  (PowerPoint file)

• Learning Morse Code 
  Hams enjoy making HF CW contacts with simple inexpensive rigs.  Code readers are ineffective at decoding hand sent conversational CW.