What is a non-fungible token

Is also called an NFT.  It is a unique token that can’t be interchanged with any other token on the same blockchain (or ANY other blockchain). 

An NFT is used to represent and prove ownership of a very specific piece of digital data. Such as digital music, art, or identity information. Whoever owns a particular NFT is the sole owner of that thing. No other similar token could be confused as the owner of the related unique data. NFTs are currently most frequently used in digital cryptogames, but there are many more possible uses.  

Most current non-fungible tokens are built on the Ethereum standard. But there are also a few others. Currently, you can’t easily design a non-fungible bitcoin asset. 

Examples

FUNGIBLE: A dollar IS fungible, which means that it can be equally traded for another dollar. A bitcoin is also fungible and can be exchanged for any other bitcoin.  

Non-fungible: A similar (but not perfect) example could be a pair of movie tickets. Two tickets to the same theatre, but different movies and/or dates, are non-fungible – you can’t interchange them. An NTF can be thought of like that movie ticket. (except that an NTF also proves ownership and lasts eternally if not sold)

See here to find various non-fungible assets.

See also the difference between a Coin and a Token.

See Forbes report on the explosion of NFTs.