A ledger anyone can verify
A blockchain is a database copied across many computers. Transactions are grouped into blocks, and each block references the one before it. That chain of references makes past edits visible and extremely difficult to coordinate.
Public blockchains separate verification from permission. Anyone can inspect the rules and the transaction history; participation does not depend on one company maintaining the master record.
Cryptocurrency combines a shared record, economic incentives, and cryptography so strangers can agree on ownership without a central bookkeeper.
Keys, addresses, and wallets
A wallet does not hold coins like a leather wallet holds cash. It manages cryptographic keys. A public address is similar to an account number; a private key is the authority to sign a transaction.
Custodial services manage keys for you. Self-custody gives you direct control, but it also makes backup, security, and succession your responsibility. A lost private key cannot be reset by a help desk.
Transactions are signed instructions
When you send an asset, your wallet signs a message. The network verifies that signature, checks the rules, and—once consensus is reached—records the change.
How networks agree
Proof of work uses computation and energy to make rewriting history costly. Proof of stake uses locked capital and penalties to align validators with the network. Both are mechanisms for choosing a valid history under adversarial conditions.
Decentralisation is a spectrum. Node distribution, developer control, token ownership, infrastructure concentration, and governance all matter.
Why a token may have value
Value can come from scarcity, settlement demand, security budgets, access to computation, governance, collateral use, or social coordination. None of these guarantees a durable price. A useful network can still have an overvalued token; a rising token can still have weak fundamentals.
The safest starting point is to ask what the asset is needed for, who controls supply, what users pay for, and which assumptions must remain true.