Bitcoin introduced the world to a new kind of money, one that isn't controlled by any single bank or government. It's a powerful idea, but its focus is narrow: to be a secure, decentralized ledger for tracking who owns which bitcoins. Think of it like a specialized calculator, designed to do one job—and do it very well.

Ethereum, launched in 2015, asked a different question. What if we could use this same decentralized technology for more than just money? What if we could build a global, shared computer that anyone could use to run applications that are unstoppable and censorship-resistant?

This is the core purpose of Ethereum. It's not just a payment network; it's a programmable blockchain. While Bitcoin's blockchain only records transaction data, Ethereum's blockchain can store and execute computer code. This makes it more like a global smartphone than a calculator. You can still do the simple stuff (like sending money), but you can also run complex applications on top of it.

How can thousands of computers around the world act as a single, shared computer? The answer is the Ethereum Virtual Machine, or EVM.

Imagine a piece of software that runs on every single computer (or "node") connected to the Ethereum network. When someone wants to run a program, they send it to the network. Every node then runs that program inside its own copy of the EVM. Because every node is running the exact same code with the exact same starting data, they all arrive at the exact same result. This mass agreement is what makes the computation trustworthy and secure without needing a central authority.

This shared computing environment is what allows for the creation of "smart contracts"—self-executing agreements with the terms of the agreement directly written into code. The EVM ensures that the rules of these contracts are followed automatically and without fail.

Running computations across thousands of computers isn't free. The network needs a way to pay the people who contribute their computing power. This is where Ether (ETH), Ethereum's native cryptocurrency, comes in.

Ether serves two main purposes. First, like Bitcoin, it can be used as a store of value or a means of exchange. You can send ETH from one person to another. Its more critical role, however, is to function as the fuel for the Ethereum network.

Every operation on Ethereum, from a simple transaction to a complex smart contract execution, requires a certain amount of computational work. This work is measured in units of "gas." A simple transfer of ETH might cost 21,000 gas, while a more complex operation could cost millions.

When you want to perform an action on the network, you must pay a transaction fee, often called a "gas fee." This fee is calculated by multiplying the amount of gas your transaction requires by the current price of gas, which is set by network demand. You pay this fee in ETH.

This system accomplishes two things:

1. It compensates the node operators (called "validators") for the electricity and hardware they use to process transactions and secure the network.
2. It prevents the network from being spammed with endless, useless computations, since every single operation has a cost.

In short, Ethereum extends the idea of a decentralized ledger into a full-fledged global computer. It uses the EVM to run code in a distributed way, and it's all powered by its native currency, ETH, through a system of gas fees.

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