"Gas" refers to the mandatory fee you must pay in order to process any transaction or execute a smart contract “on-chain” (on the Ethereum network); it's the fuel that enables the network to operate and goes directly to the miners who keep the network going every day.
These fees are dictated by the Ethereum network and fluctuate dependent on network traffic and other factors. Gas is unrelated to Foundation marketplace fee and is not in any way controlled by Foundation -- it cannot be refunded, reimbursed, nor discounted.
Deploying a smart contract, minting an NFT, listing an NFT for auction, bidding in an auction, and settling an auction all happen on-chain and will require a gas fee to complete. All actions are recorded on the blockchain to preserve the utmost provenance for creators and collectors.
Most wallet apps make it very clear before you complete a transaction how much gas you can expect to pay in order to execute a transaction. This provides you with an opportunity to back out and wait until fees come down. You may also have the option in your wallet app to reduce your desired gas fee (and wait longer for your transaction to process), or increase them for a faster processing time. Generally speaking, sticking with your wallet's default gas setting is best.
When you pay a gas fee, it is automatically deducted from your wallet's ETH balance at the time of transaction processing (such as minting an NFT, transferring an NFT, converting ETH for another cryptocurrency, etc). Always make sure you have a bit of extra ETH to cover gas fees, or you may encounter transaction failures.
You can track gas fees here. Bookmark it! 🔖