A simplified chemical reaction method recognized in 2001 by a group led by Nobel Laureate Prof. K. Barry Sharpless at the Scripps Research Institute. “Click” is meant to signify that joining molecular pieces is as easy as clicking together the two pieces of a buckle. The buckle works no matter what is attached to it, as long as its two pieces can reach each other and the components of the buckle can make a connection only with each other. Click reactions are easy to perform, give rise to their intended products in very high yields with little or no by-products, work well under many conditions (usually especially well in water), and are unaffected by the nature of the groups being connected to each other.