Ethereum Virtual Machine (EVM) in Blockchain / Solidity - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Ethereum Virtual Machine (EVM)?

The EVM is a virtual computer that runs smart contracts on the Ethereum blockchain. It executes code exactly as programmed, ensuring all nodes agree on the results.

intermediate

How does the EVM ensure security and consistency?

The EVM runs code in a sandboxed environment, isolating it from the host system. It uses gas fees to limit resource use and prevent infinite loops, ensuring all nodes reach the same outcome.

beginner

What is 'gas' in the context of the EVM?

Gas is a unit that measures the computational work required to execute operations on the EVM. Users pay gas fees to run smart contracts, which prevents abuse and compensates miners and validators.

intermediate

Explain the role of bytecode in the EVM.

Smart contracts are compiled into bytecode, a low-level code the EVM understands and executes. This bytecode runs on every Ethereum node to maintain consensus.

intermediate

What happens if a smart contract runs out of gas during execution?

If a contract runs out of gas, the EVM stops execution and reverts all changes made during that transaction. The user still pays for the gas used until that point.

What does the EVM execute?

A Python scripts

B JavaScript code

C Smart contract bytecode

D HTML pages

The EVM executes smart contract bytecode compiled from languages like Solidity.

Why is gas used in the EVM?

A To measure and pay for computation

B To store data permanently

C To create new Ethereum accounts

D To speed up transactions

Gas measures computation cost and prevents abuse by requiring payment for resource use.

What happens if a transaction runs out of gas?

A Transaction completes successfully

B Execution stops and changes revert

C Gas is automatically refilled

D The contract code is deleted

Running out of gas stops execution and reverts all changes made during the transaction.

Which environment does the EVM provide?

A Sandboxed and isolated

B Direct access to hardware

C Cloud-based only

D Graphical user interface

The EVM runs code in a sandboxed environment to protect the host system.

What language is typically compiled into EVM bytecode?

A Ruby

B Java

C C++

D Solidity

Solidity is the main language compiled into bytecode for the EVM.

Describe how the Ethereum Virtual Machine processes a smart contract transaction.

Think about how code runs, how resources are measured, and what happens if something goes wrong.

Explain the importance of gas in the Ethereum Virtual Machine.

Consider why running code on many computers needs a cost.