It is broken down into 5 sub-waves, labeled 1, 2, 3, 4 and 5, which typically will develop inside of a trend channel (the red lines), although some occasional movements outside of the channel can be observed.
Impulse sub-waves 1, 3 or 5 will often exhibit extension. The extension of an impulse sub-wave can be broken down into five waves.
Elliott refers to the golden number of the Fibonacci sequence: 1 ;1.618 ; 2 ; 2.618 ; 4.13 etc... In the case of extensions, he observed that a wave that has been extended is 1.618 or 2 times stonger than the other waves.
Wave 2 never retraces more than 100% of wave 1
Wave 4 never penetrates into wave 1 territory
Wave 3 is never the smallest wave
In an impulse wave, one of the 3 sub-waves (1, 3 or 5) is extended