An Introduction to Blockchain, Bitcoin, Ethereum, and ICOs

Blockchain is a multi‑party maintained data structure that stores information in linked blocks, using cryptography to ensure secure transmission, immutability, and non‑repudiation.

Each block consists of a header (containing timestamp, previous‑block hash, Merkle root, and nonce) and a body that holds the actual transaction data.

Key cryptographic concepts include hash functions (e.g., MD5) for data integrity verification and asymmetric encryption with public‑private key pairs for secure communication.

Bitcoin, created by the pseudonymous Satoshi Nakamoto, was the first peer‑to‑peer electronic cash system built on blockchain, maintaining a distributed ledger of all transactions.

Mining involves participants running specialized hardware to solve proof‑of‑work puzzles; successful miners receive newly minted bitcoins and transaction fees, with block rewards halving roughly every 210,000 blocks (approximately every four years).

A typical Bitcoin transaction (e.g., A sending 10 BTC to B) follows steps: verify addresses, sign the transaction with the sender’s private key, broadcast to the network, have miners include it in a new block, compute a valid hash meeting difficulty criteria, timestamp the block, and finally add the block to the chain.

Ethereum, founded by Vitalik Buterin, extends blockchain functionality by providing a decentralized virtual machine (EVM) that can execute Turing‑complete smart contracts, enabling a wide range of decentralized applications beyond simple currency.

Smart contracts are programs stored on the blockchain that run in the EVM; each transaction that invokes a contract must specify a gas limit and gas price, ensuring computational resources are paid for.

Initial Coin Offerings (ICOs) allow projects to raise funds by selling newly issued tokens in exchange for established cryptocurrencies; however, many jurisdictions, including China, have classified ICOs as illegal fundraising activities.

The article also discusses market realities such as mining hardware costs, the prevalence of fabricated trading volumes on exchanges, and the broader adoption of blockchain by various internet companies.