What is 'click chemistry', which won trio of scientists the Nobel Prize?

The 'Click Chemistry' that won Morten Meldal, Barry Sharpless, and Carolyn Bertozzi this year's Nobel Prize in Chemistry is about making difficult processes easier. Click chemistry and bioorthogonal reactions - which take place without disrupting the normal functioning of the cell - have taken chemistry into the era of functionalism, bringing the greatest benefit to humankind.