Bitcoin Fundamentals

Bitcoin is a peer-to-peer monetary network, and bitcoin, commonly represented by BTC, is its native digital asset. Participants can transfer value using transactions authorized by cryptographic spending conditions rather than a central account administrator. Full nodes independently verify those transactions and the blocks containing them, while miners compete through proof of work to extend the valid transaction history. Bitcoin's issuance schedule reduces the block subsidy over time and limits the possible supply to approximately 21 million coins under its established rules. Each BTC is divisible into 100 million satoshis, allowing transfers smaller than one coin. The ledger is public and pseudonymous, not automatically anonymous. BTC should also be distinguished from wrapped representations, exchange account balances, and separately issued tokens associated with the Bitcoin ecosystem. Those products can introduce additional custodians, contracts, or indexing rules that are not part of holding native BTC directly.

Sources: bitcoin.org · bitcoin.org

Bitcoin Core is an open-source software project that provides a widely used implementation of a Bitcoin full node, together with wallet and developer interfaces. A node running the software can validate blocks and transactions, maintain its view of the blockchain, and communicate with peers without accepting another company's ledger as authoritative. Its wallet capabilities can generate addresses, track funds, and help construct and sign transactions when configured for that purpose. Bitcoin Core is not the Bitcoin network itself, an exchange, or a company that can reverse payments. Publishing a software release also does not automatically force every participant to adopt new rules. Operators decide what software to run, and consensus compatibility determines whether their nodes follow the same valid history. Understanding this distinction helps explain why a development proposal, a released feature, and an activated network rule are different stages rather than interchangeable events.

Sources: bitcoincore.org · github.com

A block is a structured collection of transaction data that a blockchain records as one step in its history. A Bitcoin block contains a header and a list of transactions, beginning with a special coinbase transaction. The header links to a previous block and commits to the included transactions through a Merkle root. Miners search for a header hash that satisfies the proof-of-work target, but finding such a hash is only one requirement for acceptance. Full nodes also check transaction validity and other consensus limits. A block can be valid without remaining in the eventual best chain if competing branches are discovered. The term therefore describes a data structure, not an unconditional promise of final settlement. Block explorers display its hash, height, timestamp, transaction count, and other details, each of which answers a different question about the recorded history.

Sources: developer.bitcoin.org · bitcoincore.org

A block explorer is a website or application that presents blockchain records in a searchable format. It can help users look up a transaction identifier, inspect a block, examine outputs associated with an address, or estimate how many confirmations a payment has received. The displayed information is usually assembled by software that queries and indexes a node's data. An explorer is a viewing service, not the authority that makes transactions valid. Its labels, address groupings, fee estimates, and token interpretations may include assumptions beyond the underlying ledger. A missing result can reflect an indexing delay, a network mismatch, or an unconfirmed transaction the service has not seen. Looking up an address on a public service can also reveal interest in that address to the operator. For sensitive verification, distinguish raw blockchain evidence from the explorer's additional presentation and analysis.

Sources: bitcoincore.org · bitcoincore.org

Block height is a block's position within a particular blockchain history, counted from the genesis block at height zero. Its immediate successor has height one, and each later block increases the height by one along that branch. Height is useful for describing confirmation depth, scheduled events, and restrictions that depend on the number of blocks rather than clock time. It is not a globally unique block identifier: competing branches can contain different blocks at the same height. A block hash identifies the particular block more precisely. Height also should not be treated as an exact calendar. Bitcoin targets an average block interval, but individual blocks can arrive sooner or later. When a chain reorganization replaces recent blocks, the block associated with a particular height can change even though the numbering system itself stays the same.

Sources: bitcoincore.org · bitcoincore.org

The genesis block is the starting block of a blockchain, assigned height zero. Unlike later blocks, it does not extend an earlier block within that chain. Bitcoin software identifies a specific genesis block as part of its network configuration, establishing the initial reference from which subsequent block relationships are traced. Different networks, including testing environments, can have different genesis blocks even when they use related software. The term describes a technical starting point, not a guarantee that a project is decentralized or trustworthy. A new cryptocurrency can create its own genesis block while choosing very different rules for issuance, permissions, and validation. When examining network data, the genesis reference helps distinguish one chain from another. It also illustrates why a copied codebase does not automatically share Bitcoin's transaction history, accumulated proof of work, or native BTC balances.

Sources: github.com

A satoshi, often shortened to sat, is the smallest whole unit used in Bitcoin's base-layer value accounting. One bitcoin equals 100 million satoshis, so one satoshi is 0.00000001 BTC. Wallets can display the same underlying amount in either denomination, which can make small payments easier to read without changing their value. Transaction fee rates are often quoted in satoshis per virtual byte rather than as a percentage of the payment. Some higher-layer systems use finer internal accounting units, but Bitcoin transaction output amounts remain denominated in whole satoshis. A satoshi is a unit of BTC, not a separate cryptocurrency or an independently issued token. Ordinals-related software can track particular satoshis through an additional convention, but the base protocol does not assign a larger face value to one because of its number, history, or collectible description.

Sources: github.com