Ethereum Virtual Machine (EVM): A Comprehensive Guide

The Ethereum Virtual Machine (EVM) is a decentralized virtual environment that executes code securely and consistently across all Ethereum nodes. Nodes run the EVM to process smart contracts, using gas to measure computational effort for operations, ensuring efficient resource allocation and network security.

Prerequisites

To grasp EVM concepts, familiarity with computer science terms like bytes, memory, and stack is essential. Knowledge of cryptographic fundamentals such as hash functions and Merkle trees is also beneficial.

From Ledger to State Machine

While blockchains like Bitcoin are often described as "distributed ledgers," Ethereum transcends this analogy by functioning as a distributed state machine. Its state is a vast data structure storing account balances and a machine state capable of executing arbitrary code via predefined rules—governed by the EVM.

Key Differences:

Bitcoin: Tracks currency transactions (UTXO model).
Ethereum: Manages a dynamic state with executable smart contracts.

Ethereum State Transition Function

EVM operates as a deterministic mathematical function:

Y(S, T) = S'

Inputs:
- S: Current state.
- T: Set of valid transactions.
Output: New state S'.

Components:

State: A Merkle Patricia Trie linking all accounts via hashes.
Transactions: Cryptographically signed instructions, either:
- Message calls (interacting with contracts).
- Contract creations (deploying new bytecode).

EVM Architecture

Core Features:

Stack Machine: Depth of 1,024 items (256-bit words).
Transient Memory: Byte-addressable, reset post-transaction.
Persistent Storage: Merkle Patricia Trie tied to contracts.

Opcodes:

EVM executes bytecode via opcodes like:

Arithmetic (ADD, SUB).
Cryptographic (SHA3).
Blockchain-specific (BALANCE, BLOCKHASH).

👉 Discover how EVM opcodes optimize smart contracts

EVM Implementations

All implementations adhere to the Ethereum Yellow Paper. Notable versions include:

| Implementation | Language |
|---------------|----------|
| Py-EVM | Python |
| evmone | C++ |
| ethereumjs-vm| JavaScript |
| revm | Rust |

Frequently Asked Questions (FAQ)

1. What is gas in EVM?

Gas measures computational work, preventing infinite loops and spam. Users pay gas fees for transactions.

2. How does EVM ensure security?

By isolating contract execution in a sandboxed environment, limiting access to external systems.

3. Can EVM run non-Solidity languages?

Yes! Via compilers like Vyper or LLVM-based tools.

👉 Explore EVM-compatible blockchains