The CuAAC "click" reaction has developed as one of the most useful and widely employed reactions in ligation within polymer chemistry. This is due to the unique properties of the Cu(I) catalysis which renders the reaction quantitative even at low concentrations, orthogonal with other chemistries and extremely robust. The formed triazole on the other hand is of intermediate polarity and chemically and biochemically "invisible", and the CuAAC provides the ideal "click" reaction for stitching together polymer architectures of unprecedended complexity as was it molecular LEGO. The CuAAC "clicking" in polymer chemistry is increasing exponentially and lead to highly defined polymer materials with novel properties.