Gas and transaction fees

When you send a transaction on a blockchain, you pay a small fee. On Bitcoin it is just called the transaction fee. On Ethereum and most other smart contract chains it is called gas. The names are different, but the idea is the same: the network charges you to use it.

There are two reasons for this. The first is to keep spam out: if every transaction were free, attackers could flood the network with junk. The second is to pay the validators who actually do the work of including your transaction in a block. The fee is the price of the network's attention.

Why call it "gas"?

On Ethereum, every operation a transaction performs (transferring tokens, calling a contract, storing data) costs a specific number of "gas units." Sending a simple transfer might cost 21,000 units. Calling a complex contract might cost 200,000. The total fee you pay is the gas units used multiplied by the gas price you are willing to pay per unit.

The metaphor is a car. The work you want done is the trip. Different trips burn different amounts of fuel. The price of fuel changes depending on the day. Your bill is fuel used times price per unit.

Why fees spike

Each block on the chain has limited room. If too many people want to transact at the same time, they bid against each other for that space, the same way an auction works. During quiet periods, the gas price is low and a transfer might cost a few cents. During famous moments — a hot NFT mint, a market crash, a viral meme coin launch — the gas price can spike to where a single transaction costs $50, $100, or more.

You set a maximum gas price you are willing to pay. Higher bids get included sooner. Lower bids wait. If you bid below market, your transaction sits in the queue and might never be confirmed.

A typical fee, by chain

Different blockchains make different trade-offs. Older, more conservative networks like Bitcoin and Ethereum charge more because security and decentralization are prioritized over cheapness. Newer chains and "Layer 2" networks built on top of Ethereum compress many transactions into one, which slashes the per-user cost.

Layer 2: cheaper Ethereum

A "Layer 2" (or L2) is a separate blockchain that runs on top of Ethereum and posts compressed batches of its activity back to the main chain. Networks like Arbitrum, Base, and Optimism are all L2s. They feel like Ethereum, use the same wallets, but charge a fraction of the gas because hundreds of users share the cost of one big batch.

For most everyday users, this is where Ethereum is actually used now. The expensive mainnet is increasingly a settlement layer where the L2s anchor their security.

Practical lessons

• Check the current gas price before transacting. Wallets show it; sites like etherscan.io track it in real time.
• If you do not need a transaction confirmed immediately, set a lower bid and wait.
• Doing many actions in one batch (like a single contract call instead of three) saves gas.
• For small amounts, use an L2 instead of mainnet. The savings are usually 10x to 100x.
• Failed transactions still consume gas. Read the error before retrying with a higher bid.

On a public blockchain, attention is rationed by money. The market sets the price.

Now that you know how transactions get paid for, the next obvious question: what about the wild price swings? Most people who actually use crypto for payments do not use volatile coins like ETH. They use stablecoins, and that is what we cover next.