Gas and transaction fees in Blockchain / Solidity - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is 'gas' in blockchain transactions?

Gas is a unit that measures the amount of computational effort required to execute operations on a blockchain like Ethereum. It helps pay for transaction processing.

beginner

Why do blockchain transactions require fees?

Fees pay miners or validators to process and confirm transactions. They prevent spam and ensure network security by rewarding those who maintain the blockchain.

intermediate

What happens if you set a low gas price for a transaction?

The transaction may take longer to be processed or might not be processed at all because miners prioritize transactions with higher fees.

intermediate

How is the total transaction fee calculated?

Total fee = Gas used × Gas price. Gas used is how much work the transaction needs, and gas price is how much you pay per unit of gas.

intermediate

What is the difference between 'gas limit' and 'gas price'?

Gas limit is the maximum gas you allow for a transaction to use. Gas price is how much you pay per unit of gas. Together they control the max fee you pay.

What does 'gas' measure in a blockchain transaction?

A Computational work needed

B Amount of cryptocurrency sent

C Time taken to confirm transaction

D Number of users on the network

Gas measures the computational work required to execute a transaction or contract.

Why might a transaction with a low gas price take longer to confirm?

A Low gas price means more work needed

B It uses less gas overall

C Miners prefer transactions with higher fees

D It is automatically rejected

Miners prioritize transactions that pay higher fees to maximize their rewards.

How do you calculate the total fee paid for a transaction?

A Gas price divided by gas used

B Gas limit plus gas price

C Gas limit minus gas used

D Gas used multiplied by gas price

Total fee = Gas used × Gas price.

What is the purpose of setting a gas limit?

A To limit the maximum gas spent on a transaction

B To set the price per gas unit

C To speed up the transaction

D To increase the transaction size

Gas limit sets the maximum gas the transaction can consume to avoid overspending.

Which of these is NOT true about transaction fees?

A They reward miners or validators

B They guarantee instant transaction confirmation

C They depend on gas price and gas used

D They prevent network spam

Fees do not guarantee instant confirmation; higher fees increase priority but confirmation depends on network conditions.

Explain how gas and gas price work together to determine transaction fees.

Think about how much work is done and how much you pay for each unit of work.

Describe why transaction fees are important for blockchain networks.

Consider what motivates people to keep the network running and safe.