GAS is the cost to perform a transaction on a blockchain network. Gas price is set by miners based on the supply and demand of computational power to process smart contracts and other transactions.
EVERY transaction needs to be verified so every transaction will cost gas, contract deployment, minting, buying, selling...
Gas fees are measured in GWEI, which denotes a “giga-wei.” One gwei is 0.000000001 ETH. When submitting an order for a transaction, users must indicate a "GAS LIMIT" which is the MAXIMUM amount they’re willing to pay to have their transaction added to the blockchain.
Gas will be the same for the deployment of a 100 piece collection, 1000 piece collection or 10000 piece collection.