NVT is an acronym that stands for Network Value to Transactions Ratio.
Created by well-known cryptocurrency figure Willy Woo, the NVT ratio is the cryptocurrency equivalent to the traditional P/E (price-to-earnings) ratio.
The NVT ratio is used to indicate whether the value of the network is greater the value being transmitted over it.
Simplified example:
If the Bitcoin network is worth 100,000,000,000 (100Billion) and the on-chain value being transmitted is 100,000,000 (100Million) then the NVT is 100; stating that the network is overpriced in comparison to the actual utility that it is providing.