How the EVM Works

How the EVM Works

The Ethereum Virtual Machine (EVM) is the runtime environment for smart contracts in the Ethereum blockchain. It is a decentralized, blockchain-based computing platform that executes code exactly as it is written, allowing developers to build and deploy decentralized applications (dApps) on the Ethereum network.

At the heart of the EVM are its opcodes, or operation codes. These are the instructions that are executed by the EVM when a smart contract is run. Each opcode corresponds to a specific operation, such as pushing data onto the stack, comparing values, or calling other contracts.

When a smart contract is deployed to the Ethereum blockchain, it is first compiled into bytecode, which is the EVM's low-level, binary representation of the contract's code. This bytecode is then stored on the blockchain and can be executed by any node on the network.

When a contract is executed, its bytecode is run through the EVM, and each opcode is executed in turn. This process is known as "executing" the contract. The EVM keeps track of the state of the contract's execution, including the values of its local variables, as well as its access to the Ethereum blockchain and any external data sources.

One of the key features of the EVM is the use of gas to compute the cost of executing a contract. Gas is a unit of measure for the computational resources required to execute a contract. Every opcode has a specific gas cost associated with it, and the total gas cost of a contract is the sum of the gas costs of all the opcodes it contains.

The use of gas in the EVM serves several important purposes. First, it acts as a deterrent against malicious or excessively complex contracts that could bog down the network by requiring too many resources to execute. Second, it allows the network to properly allocate its resources by prioritizing contracts that have a higher gas price (i.e. are willing to pay more for the computation).

In terms of storage, the EVM uses a simple key-value store to keep track of the values of local variables and other data used by contracts. This store is analogous to a simple database, where each contract has its own "table" of data that it can access and manipulate.

Common data structures, such as arrays and objects, can be implemented in the EVM using this key-value store. For example, an array can be represented as a series of keys, where each key corresponds to an index in the array and the value associated with that key is the element at that index. Similarly, an object can be represented as a set of keys, where each key corresponds to a property of the object and the associated value is the property's value.

In conclusion, the EVM is a critical component of the Ethereum blockchain, enabling the execution of smart contracts on the decentralized network. Its opcodes, execution model, gas computation, and storage mechanisms provide the foundation for a wide range of dApps and other decentralized applications.