Gas, fees, and why your $5 became $4.80

Every action on a chain — sending, swapping, minting — costs a small fee, usually called gas. It pays the computers that keep the notebook honest. Fees vary by chain: Ethereum mainnet can charge dollars, Solana charges fractions of a cent.

Swaps also have two quieter costs. Slippage: between clicking and confirming, the price moves, and you get slightly less than quoted. And price impact: if you buy a big chunk of a small token, your own order pushes the price up while you're buying.

Scam flavor to know: fake "gas fee" popups asking you to approve weird amounts, or sites claiming you must "verify your wallet" with a payment. Real gas is paid automatically in the native coin when you transact — nobody legitimate DMs you an invoice for it.