When using a smart contract blockchain, users have to pay a fee to miners/validators so they include their transaction into the next block to get executed. The fee is called gas and how much of it you need to pay depends on the complexity of the transaction. But while the amount of gas needed for a contract remains constant over time, the price of gas does not, being subject to market forces of supply and demand. *While there is more to say on the subject of gas, Etherscan says it better. In ...