Block
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In Brief
A node is any computer that connects to a blockchain network and helps maintain it by storing, validating, and relaying transactions and blocks.
What Is a Block?
A block is a container that records a batch of validated transactions on a blockchain. Each block is cryptographically linked to the one before it, creating a continuous, tamper-resistant chain — which is exactly where the word "blockchain" comes from.
Once a block is added and confirmed by the network, the transactions inside it become a permanent part of the ledger that cannot be altered or removed.
What's Inside a Block?
| Component | Description |
|---|---|
| Block header | Metadata about the block |
| Previous block hash | Links this block to the one before it |
| Transactions | The validated transactions in this block |
| Timestamp | When the block was created |
| Nonce | The value miners adjust in Proof of Work |
| Merkle root | A single hash summarizing all transactions |
How Does a Block Get Added?
Pending transactions are gathered from the mempool into a candidate block.
The network validates the transactions and the block according to its consensus rules (Proof of Work, Proof of Stake, etc.).
The block is given a hash that includes the previous block's hash.
Once accepted, the block is broadcast and added to every node's copy of the chain.
Subsequent blocks build on top of it, increasing the number of confirmations and making it harder to reverse.
Block Time and Block Size
Block time — the average interval between blocks. Bitcoin targets ~10 minutes; Ethereum is ~12 seconds.
Block size / gas limit — limits how many transactions or how much computation a block can hold, affecting throughput and fees.
What Is a Block Confirmation?
A confirmation is added each time a new block is built on top of the block containing your transaction. More confirmations mean greater certainty that a transaction is final and irreversible. Many services consider a Bitcoin transaction settled after several confirmations.
The Genesis Block
The very first block of a blockchain is called the genesis block. It is hard-coded into the protocol and has no previous block to reference. Bitcoin's genesis block was mined on January 3, 2009.
Blocks and Trust Wallet
When you send a transaction in Trust Wallet, it is broadcast to the network and waits to be included in a block. Once confirmed, you can track it via its transaction hash on a block explorer. As a non-custodial wallet, Trust Wallet lets you send and receive transactions across 100+ blockchains while you keep full control of your private keys.