Podstawy Ethereum i EVM

Ethereum is more than a coin - it's an open, decentralized platform for running smart contracts and building decentralized apps (dApps).

Every operation on Ethereum costs a fee paid in Ether (ETH). Gas measures the computational work a transaction needs - think of it as fuel, paid in ETH.

Ethereum has two account types: EOAs, controlled by a private key (a person), and contract accounts, controlled by their deployed code. Both have an address and hold ETH.

A transaction is a signed message between accounts. It can transfer ETH, deploy a new contract, or call a function on an existing one - and always costs gas.

Smart contracts are programs on the blockchain that run automatically when conditions are met. They enforce agreements without intermediaries, and once deployed they're immutable.

The Ethereum Virtual Machine (EVM) is the runtime that executes smart contracts - a single global, decentralized computer shared by the whole network.

Your Solidity contract is compiled to bytecode, which the EVM interprets and runs. Every node runs the EVM identically, so results match across the network.

The EVM runs low-level opcodes like ADD, PUSH, and MSTORE. Your Solidity compiles down to these, and calling a contract executes the right opcode sequence.

Every opcode has a gas cost. This stops infinite loops and spam - and if a transaction runs out of gas it reverts, undoing changes while still charging the gas spent.

The EVM gives smart contracts determinism (same code, same result on every node), sandboxed isolation, and security via gas limits that block resource-exhaustion attacks.

Recap: Ethereum runs smart contracts via the EVM, paid for in ETH and gas. EOAs and contract accounts interact through signed transactions executed as bytecode.