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In the world of blockchain, the Ethereum Virtual Machine (EVM) stands as a central and indispensable piece of the puzzle. It's the software responsible for executing smart contracts, enabling decentralized applications, and facilitating secure and transparent transactions. In this article, we'll take you on a journey to unravel the wonders of the EVM, exploring what it is, how it came into existence, and the pivotal role it plays in the realm of blockchain.

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## Ethereum Virtual Machine Explained

thereum Virtual Machine, or EVM, is a powerful and versatile software environment that runs on the Ethereum network. Think of it as a global, decentralized computer that processes code and executes smart contracts. Smart contracts are self-executing agreements with the terms of the contract between buyer and seller being directly written into lines of code. EVM is responsible for the execution of these contracts, ensuring that they perform as intended.

The EVM is often compared to a real-world computer, but it operates in a different realm. It is [Turing-complete](https://www.geeksforgeeks.org/what-is-meant-by-turing-complete-in-ethereum/), meaning it can perform any computation that can be described algorithmically. However, there's a twist – it's not entirely unlimited in its capabilities. The EVM is intrinsically bounded by a parameter called "gas," which limits the total amount of computation it can perform. This limitation ensures that malicious or poorly written code cannot overburden the network, making it a secure and reliable platform. Hence we call it as quasi-turing-complete.

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## Brief History of EVM

 Ethereum Virtual Machine came into existence alongside the Ethereum blockchain, which was proposed by a young, brilliant developer named Vitalik Buterin in late 2013. The Ethereum project gained widespread attention and quickly attracted the interest of Web3 enthusiasts and developers. The concept of a decentralized platform that could run applications without the need for a central authority captured the imagination of the blockchain community.

Ethereum's development team, led by co-founder Gavin Wood, began crafting the technical underpinnings of the platform. This included the creation of the EVM, the engine that powers Ethereum's unique capabilities. Gavin Wood, an accomplished computer scientist and one of the co-founders of Ethereum, played a pivotal role in shaping the EVM and Solidity, Ethereum's programming language for smart contracts.

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## Virtual Machine - A Primer

### Exploring the World of Virtual Machines

Before we delve into the intricacies of the Ethereum Virtual Machine (EVM), let's first demystify the concept of a virtual machine (VM) itself. VMs are like computers within computers, serving a variety of purposes. Let's uncover the basics of virtual machines, their architecture, and why they are crucial in modern computing.

### What is a Virtual Machine?

At its core, a virtual machine (VM) is a software-based emulation of a physical computer. It's as if you're running a computer within your computer, creating a self-contained environment where you can execute software just like you would on a physical machine. This virtualization concept is a game-changer in computing, and here's why.

### The Architecture of Virtual Machines

![virtual machine architecture ](https://ds-storage.sgp1.cdn.digitaloceanspaces.com/blocktheory/website/strapi/uploads/1313c6189669d88735e20acbefe3c748.png)

Virtual machines have their own architecture, which consists of two primary components:

**1. The Hypervisor:** This is the software that manages and controls the VMs. It's responsible for allocating resources and ensuring that each VM runs smoothly without interfering with others.

**2. Virtual Machine Monitor (VMM):** The VMM is the secret sauce that enables VMs to function. It provides an isolated space for each VM, ensuring that they can't interfere with each other or the host system.

These components work together seamlessly to create a virtual environment that mimics a physical computer. The VMs within this environment are often referred to as guests, while the underlying physical system is the host.

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## Architecture of EVM

![architecture of evm.png](https://ds-storage.sgp1.cdn.digitaloceanspaces.com/blocktheory/website/strapi/uploads/9a1edaf5f4f37ce8c9a6baf81ca9be3e.png)

Understanding the architecture of the EVM is key to comprehending its functioning. It operates on a stack-based system, maintains state and storage components, and relies on opcodes for executing smart contracts. Additionally, we'll explore the concept of "gas" and why it's intrinsic to the EVM's operation.

### How the Stack Works

Imagine a stack of plates in a cafeteria. You can add a plate to the top of the stack, and when it's time to take a plate, you naturally pick the one from the top. Similarly, in a stack-based system, you push data onto the top of the stack and pop data off the top as needed for calculations.

![Stack.png](https://ds-storage.sgp1.cdn.digitaloceanspaces.com/blocktheory/website/strapi/uploads/ec0011c2cbfab968e50961e9539a529e.png)

🤿 The word size of the machine (and thus size of stack items) is 256-bit. This was chosen to facilitate the Keccak256 hash scheme and elliptic-curve computations. The memory model is a simple word-addressed byte array. The stack has a maximum size of 1024. The EVM also has an independent storage model; this is similar in concept to the memory but rather than a byte array, it is a word addressable word array. 

Unlike memory, which is volatile, storage is non volatile and is maintained as part of the system state. All locations in both storage and memory are well-defined initially as zero. The machine does not follow the standard von Neumann architecture. Rather than storing program code in generally-accessible memory or storage, it is stored separately in a virtual ROM interactable only through a specialised instruction. 

The machine can have exceptional execution for several reasons, including stack underflows and invalid instructions. Like the out-of-gas exception, they do not leave state changes intact. Rather, the machine halts immediately and reports the issue to the execution agent (either the transaction processor or, recursively, the spawning execution environment) which will deal with it separately.

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## State and Storage Management

In the Ethereum ecosystem, the Ethereum Virtual Machine maintains two crucial components: the state and storage.

### 1. The State

The state represents the current condition of all accounts on the Ethereum network. Each account has a state, including information such as its balance and contract code. When a smart contract executes, it can read from and write to the state, updating the values associated with Ethereum addresses.

State management is fundamental to Ethereum's decentralized nature. The state of all accounts is maintained and updated across the entire network. The EVM ensures that this state remains consistent, even in a trustless and distributed environment.

### 2. Storage

While the state represents the current condition of Ethereum accounts, storage is where contract data is permanently saved. Storage is used to store data that persists across multiple transactions and block confirmations. This data can include contract variables, records of transactions, and more.

Ethereum's ability to store data in a decentralized and immutable way is a critical feature that underpins smart contract functionality. The EVM manages this storage, ensuring that data remains accessible and unchanged over time.

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## Opcodes and Smart Contract Execution

The Ethereum Virtual Machine relies on a set of instructions called opcodes to execute smart contracts. Opcodes are predefined commands that dictate specific actions within the EVM. These opcodes are included in the bytecode of a smart contract, and the EVM interprets and executes them.

Each opcode corresponds to a particular operation, such as adding two numbers, checking the balance of an account, or transferring funds between accounts. Smart contracts are essentially sequences of these opcodes, which the EVM processes in a step-by-step manner.

Smart contract developers use opcodes to define the rules and behavior of their contracts. The EVM's opcode set is intentionally limited to maintain efficiency and security while enabling powerful functionality.

| OPCODE | NAME | MINIMUM GAS | STACK INPUT | STACK OUTPUT | DESCRIPTION |
| --- | --- | --- | --- | --- | --- |
| 00 | STOP | 0 |  |  | Halts execution |
| 01 | ADD | 3 |   a                 b | a + b | Addition operation |
| 02 | MUL | 5 |   a                 b  | a * b | Multiplication operation |
| 03 | SUB | 3 |   a                 b | a - b | Subtraction operation |
| 04 | DIV | 5 |   a                 b | a / b | Integer division operation |

You can see the full list of [opcodes here](https://www.evm.codes/?fork=shanghai)

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## How EVM Works

### Bringing Smart Contracts to Life

EVM's primary role is to take the code written in Solidity or Vyper or Yul language EVM compatible langauge for smart contracts, and execute it on the Ethereum blockchain. Here's how the process works:

- **Smart Contract Deployment:** Smart contract developers create their applications in Solidity / Vyper / Yul. Once the code is ready, it's compiled into byte code.
- **Blockchain Transaction:** When a user initiates a transaction on the Ethereum network, such as interacting with a DApp or sending Ether, it includes instructions for executing smart contracts/transactions.
- **Mining and Consensus:** Miners, who validate and add transactions to the blockchain, pick up the transaction. They run the bytecode through the EVM to execute the smart contract's code.
- **State Changes:** The EVM executes the contract's code and may result in state changes, such as transferring funds between accounts or updating data. These state changes are crucial as they define how the blockchain evolves over time.
- **Gas Consumption:** Gas, the computational resource unit, is used during execution. Each operation consumes gas, and transactions require users to pay gas fees. Gas ensures that the network remains efficient and that malicious or poorly written code doesn't disrupt it.
- **Consensus and Confirmation:** After execution, miners reach consensus on the validity of the state changes. Once confirmed, these changes are permanently recorded on the blockchain.

### The Role of Miners

Miners play a crucial role in the execution process. They select transactions from the pool, execute the associated smart contracts, and attempt to reach consensus with other miners. Here's how miners contribute:

- **Smart Contract Execution:** Miners execute the bytecode of the smart contract using the EVM. They initiate the code and produce the resultant state.
- **Validation and Consensus:** Miners validate that the state changes are consistent with the transaction's intent. They ensure that the execution adheres to the rules of the EVM and the Ethereum protocol. Miners compete to find the next block, with the first miner to achieve consensus earning a reward.
- **Recording State Changes:** Once consensus is reached, the state changes are permanently recorded on the blockchain. This forms a new block in the chain.

### The Need for Gas

Gas is a unique aspect of Ethereum's operation. It ensures that computation on the blockchain remains efficient and secure. Gas limits the amount of work a smart contract can perform in a single transaction, preventing it from running indefinitely. This mechanism is crucial for network stability and protection against malicious code.

The Ethereum Virtual Machine acts as the engine behind the execution of smart contracts and DApps on the Ethereum blockchain. It translates code written in Solidity into real-world actions, ensuring security, transparency, and efficiency. Miners validate transactions, execute smart contracts using the EVM, and reach consensus, while gas ensures that the network remains reliable and secure.

With a clear understanding of how the EVM operates, you can better appreciate the remarkable capabilities it brings to the world of blockchain and decentralized applications.

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## Pros of EVM

The Ethereum Virtual Machine (EVM) and the broader Ethereum ecosystem come with a myriad of advantages:

### Smart Contract Capabilities

Smart contracts, executed by the EVM, enable self-executing agreements without the need for intermediaries. These contracts can automate complex processes, such as financial transactions, without relying on a third party. The EVM ensures that smart contracts execute faithfully, increasing trust and efficiency in various applications.

### Security Features

EVM's architecture is designed with security in mind. By employing a stack-based system, gas mechanisms, and limited opcodes, it mitigates vulnerabilities that could be exploited by malicious actors. This focus on security has made Ethereum a preferred platform for DeFi, NFTs, and various blockchain applications.

### Transparency in the System

Ethereum's blockchain is public and transparent. The EVM records all transactions and smart contract executions on the blockchain, creating an immutable ledger of activities. This transparency fosters trust and accountability in a wide range of applications, from financial services to supply chain management.

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## Cons of EVM

No technology is without its challenges. In this section, we'll explore the limitations of the EVM, including scalability issues, the impact of gas costs, and the complexities involved in development.

### Scalability Issues

One of the most prominent and widely recognized limitations of the Ethereum platform is its scalability. Scalability refers to a blockchain's ability to handle a growing number of users and transactions while maintaining efficiency and speed. Ethereum, like many other blockchain networks, faces challenges in this regard.

### Gas Costs and Network Congestion

Gas, the mechanism designed to limit computation, also contributes to scalability challenges. During times of high demand, gas prices can skyrocket, making transactions and smart contract executions costly and sometimes economically unviable. This not only affects individual users but also poses a barrier to entry for developers looking to build DApps on the Ethereum platform.

### Development Complexity and Barriers

Developing on the Ethereum platform, especially for newcomers, can be challenging. Ethereum employs its unique programming language, Solidity, which developers must learn to write smart contracts. Writing secure and bug-free smart contracts adds to the complexity.

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## Conclusion

In conclusion, the Ethereum Virtual Machine (EVM) is at the core of Ethereum's transformative capabilities. As a platform that executes smart contracts and drives the world of decentralized applications, the EVM enables secure and transparent transactions while offering both benefits and challenges. The EVM is a symbol of blockchain's potential to reshape industries and processes, and its continued evolution is poised to overcome current limitations. While challenges remain, the EVM remains a beating heart of innovation in the blockchain space.


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Delve into the intricate architecture of the Ethereum Virtual Machine (EVM), the cornerstone of Ethereum's decentralized ecosystem and foundation upon which smart contracts and DApps are built. 