Click chemistry, as the name suggests, is a way of building molecules like snapping Lego blocks together. It takes two molecules to click, so researchers refer to each one as click partners.

K. Barry Sharpless and Morten Meldal independently discovered that azide, a high-energy molecule with three nitrogens bonded together, and alkyne, a relatively inert and naturally rare molecule with two carbons triple-bonded together, are great click partners in the presence of a copper catalyst. They found that the copper catalyst can bring the two pieces together in an optimal arrangement that snaps them together. Prior to this technique, researchers did not have a way to quickly and precisely make new molecules under accessible conditions, like using water as a solvent at room temperature.