There is lots of history on http://en.wikipedia.org/wiki/Morse_code relating to the history of CW which is not relevant here.
Start of Work (CT) _ . _ . _
Invitation to Transmit (KN) _ . _ _ .
End of Work (VA) . . . _ . _
End of Message (AR) . _ . _ .
Invitation to Transmit (K) _ . _
Invitation to a particular station to transmit (KN) _ ._ _.
Spacing and length of Morse code elements
In order that the Morse code sounds correct and it is easy to read, it is essential that the correct ratios of the different elements are maintained. If the different ratios are not maintained, then the Morse code becomes difficult to read and less pleasant to listen to. The agreed ratios and lengths of the different Morse code element are given below:
A dash is equal to three dots
The space between elements which form the same letter is equal to one dot.
The space between two letters is equal to three dots
The space between two words is equal to seven dots
There is no REQUIREMENT to learn morse, but I’d recommend it as you never know when you might need it Try LCWO