Zora is a portal that creates Ethereum (ETH) blockchain transactions to mint your media token using your connected wallet. Your wallet is used to pay the ETH gas fee.
Gas is essential to the Ethereum network. It is the fuel that allows it to operate, in the same way that a car needs gasoline to run. Gas refers to a fee that is required to successfully conduct a transaction on the Ethereum blockchain and keeps the network secure.
Gas fluctuates with an increased/decreased demand and the price of ETH. Due to the price fluctuation of gas the cost of minting each NFT will be different, depending on the transaction type, and ETH price. When the networks are experiencing a high volume of transactions the fee will be higher. Users are able to wait for the gas price to come down or can submit a price they are willing to pay and wait for the transaction to be confirmed. If the gas price limit is too low, miners can choose to ignore such transactions.
Learn more about how Gas works here: Gas (Ethereum)