As we know, in finance there are products such as futures, options, warrants, swaps and other products that are not assets in themselves, but depend on the price, evolution and price of another specific asset, this asset is called the underlying asset. The underlying asset is the source on which the value of financial contracts (instruments) is derived.
Suppose we have a neighbor who has a corn plantation. We need this corn for our farm, so we decided to reach an agreement with it. For this we agree with him a future price on the harvest, valued at € 1,100 (currently that same harvest is worth € 1,000), which gives us the right to acquire it in six months at the agreed price. The underlying asset would be corn, while the derivative contract would be the agreement we have reached with the neighbor. With this purchase option, we can sell it to a third party at the price we want, putting interest in the fact that perhaps corn will be more expensive in six months, or perhaps cheaper.
Some of the instruments that work with this type of asset are options and futures. These instruments allow their holder to buy or sell a certain asset (underlying) at a certain time at a previously agreed price. These instruments can be used as hedging (protection) to variations in the market, or simply as a speculative method, trying to make the most of the fluctuations in prices.