For commodity futures, it is the difference between spot price and futures price;

Spot exchange rate/spot price is higher than forward exchange rate/futures price, which is called discount; On the contrary, it is called premium.

The traditional definition is: the spot price is lower than the futures price, or the short-term futures price is lower than the long-term futures price (because of the spot inventory fee), which is a positive market; If the futures price is lower than the spot price, it is a reverse market.

Personal opinion: from the perspective of two main risk preferences in the market-the forward market is the trend of spot exchange rate/spot price and forward exchange rate/futures price close together, and may even reverse; The reverse market, on the other hand, has an increasing premium or discount-these are the two most mainstream risk preferences. The former is the mainstream for arbitrage and the latter is the mainstream for hedging.