The hidden cost of the craze for non-fungible tokens

Over the past few months a technological craze has swept the internet: the buying and selling of non-fungible tokens, or NFTs. This process uses blockchain technology to sell things like digital art, memes, tweets and videos, with NFTs from big name artists and entrepreneurs selling for millions of dollars. Laura Murphy-Oates speaks to Patrick Lum about how NFTs work, and the hidden costs that have environmentalists concerned