Gas fees are the transaction costs you pay to use a blockchain network. On Ethereum and similar chains, "gas" measures the computational effort required to execute an operation, and the fee is what you pay validators to process it.
Every action on a blockchain requires computational resources. Sending tokens, swapping on a decentralized exchange, or interacting with a smart contract all consume different amounts of gas. Simple transfers cost less gas than complex contract interactions.
On Ethereum, gas is priced in gwei (one billionth of an ETH). Since EIP-1559, each transaction has a base fee that is burned (destroyed) plus an optional priority tip that goes to the validator. The base fee adjusts automatically based on network demand: when blocks are more than 50% full, the base fee increases; when they are less than 50% full, it decreases.
Bitcoin uses a similar concept but calls them "transaction fees" rather than gas. Bitcoin fees are based on the size of the transaction in bytes rather than computational complexity. In both cases, higher fees mean faster confirmation because miners and validators prioritize the most profitable transactions in the mempool.
Gas fees directly affect the cost of using DeFi applications, trading, and transferring crypto. During periods of high network activity, fees can spike dramatically, making small transactions uneconomical. Layer-2 solutions and alternative chains exist largely to address this problem. Tracking gas prices helps you time transactions for lower costs.
The BTC Network panel on the TerminalFeed dashboard shows current Bitcoin fee estimates by priority level (low, medium, high). You can also read about how fees relate to mempool congestion in our Bitcoin Mempool guide.