Block Definition

What Is a Block?

A block is essentially a "ledger page" that packages a group of transactions along with essential metadata. Each block contains a timestamp, a block height (similar to a page number), and a cryptographic fingerprint—called a hash—that points to the previous block, linking all "ledger pages" into a continuous chain.

The hash is generated by compressing the block's data into a fixed-length value using an algorithm. Any change in the data will alter the hash, which ensures that subsequent blocks effectively "lock" prior data. The block height identifies the block's position in the chain; the genesis block is considered page 0.

How Are Transactions Organized Within a Block?

Blocks select transactions from the mempool, which acts as a “to-do list” for pending, unconfirmed transactions broadcasted to the network. Transactions offering higher fees are typically prioritized for inclusion.

To quickly verify that transactions haven’t been tampered with, each transaction’s fingerprint (hash) is paired and merged repeatedly until only a single root fingerprint remains—this structure is known as a Merkle tree. The Merkle root is stored in the block header for efficient verification.

Different blockchains impose various limits on block capacity. Bitcoin uses a maximum block size or weight limit, while Ethereum employs a gas limit—a measure of computational work allowed per block.

How Are Blocks Produced?

Blocks are produced and broadcast by block proposers. Depending on the blockchain, these may be miners or validators, but their shared goal is to periodically create new "ledger pages."

In Proof of Work (PoW), miners use computational power to "guess" solutions—a process resembling a lottery. The network automatically adjusts difficulty to maintain a target block production interval. For Bitcoin, this target remains 10 minutes per block (as of 2025, per Bitcoin protocol).

In Proof of Stake (PoS), validators lock up tokens as collateral to participate in consensus. The system randomly selects proposers. On Ethereum, blocks are produced approximately every 12 seconds (Ethereum.org docs, 2025-12), and finality is achieved through additional checks and votes.

What Is the Relationship Between Blocks and Blockchains?

A blockchain is an ordered sequence of blocks connected end-to-end over time. Each block records the hash of its predecessor, binding every "ledger page" together like pages in a book—altering an earlier page would require rewriting all subsequent pages.

When new blocks are added atop previous ones, the reliability of older blocks increases. The number of subsequent blocks is shown as "confirmations." The greater the confirmations, the lower the probability of a rollback.

How Do Blocks Differ Between Ethereum and Bitcoin?

Bitcoin and Ethereum have distinct design goals for their blocks. Bitcoin prioritizes robustness and simplicity, using size or weight limits and targeting 10-minute blocks with dynamic difficulty adjustment for stability.

Ethereum focuses on programmability, using a gas limit to control block capacity, producing blocks roughly every 12 seconds, and supporting smart contracts. Transaction fees are denominated in gas price; users can pay higher fees for faster inclusion.

Block rewards also differ. Bitcoin blocks include a "block subsidy" plus transaction fees—the subsidy halved to 3.125 BTC in April 2024 (per Bitcoin halving rules). After Ethereum’s Merge, validators are mainly incentivized by transaction fees and staking rewards (source: Ethereum.org).

How Can You View Blocks on a Block Explorer?

You can use a block explorer—a public web tool—to check block details, transactions, and address status.

Step 1: Gather an identifier such as a block height, block hash, or transaction hash.

Step 2: Enter the identifier in the explorer’s search bar to open the results page. You’ll see block time, proposer, number of included transactions, and links to adjacent blocks.

Step 3: Open the transaction list to verify amounts, recipient addresses, and fees. If the amount is correct and the status is successful, the transaction has been included in that block.

Step 4: Check the confirmation count (often labeled "Confirmations"). Gate’s deposit records also show transaction hashes—clicking them redirects you to the block explorer for confirmation progress.

What Is the Relationship Between Confirmations and User Transfers?

Confirmations count how many new blocks have been stacked on top of your target block—1 confirmation means one subsequent block, 6 confirmations provide greater security.

Deposits and withdrawals typically require a minimum number of confirmations before being credited. The requirement varies by coin and network. Gate’s deposit page displays the necessary confirmation count; once met, funds are credited automatically.

Timing depends on the chain. Bitcoin averages one block every 10 minutes, so six confirmations take about an hour. Ethereum produces blocks every ~12 seconds, so dozens of confirmations only take minutes. After several rounds of validation, Ethereum achieves "finality," minimizing rollback risk (source: Ethereum PoS design).

What Are the Risks and Common Misconceptions About Blocks?

Blocks can experience temporary forks—for example, when two proposers produce new blocks at nearly the same time. The network later selects one chain as canonical; the other becomes an orphan or reorganized branch.

Low confirmation counts carry reorg risks—if merchants release goods after zero confirmations, they may incur losses. It’s best to wait for platform-recommended confirmations or set your own safety threshold.

Setting too low of a transaction fee is another common issue; during congestion, such transactions can remain stuck in the mempool. Increasing fees or using acceleration features can help rebroadcast your transaction.

For security, beware of fake "block explorers." Always access explorers via trusted sources or from Gate’s deposit records by clicking on the hash link to avoid phishing sites.

What Is the Future of Block Design?

Block design is evolving toward greater throughput, lower costs, and enhanced data availability. In March 2024, Ethereum implemented EIP-4844 to introduce "data blobs," significantly reducing Layer 2 publishing costs (source: Ethereum Foundation blog).

Separation of block building and validation roles is also progressing—research aims to divide responsibilities between "builders" and "proposers" to reduce censorship and monopoly risks. Many chains are adopting modular architectures that separate execution from data storage, making blocks more like "data containers."

Simultaneously, Layer 2 networks aggregate large volumes of transactions before writing summaries to mainnet blocks. Thus, mainnet blocks increasingly serve as hubs for settlement and data availability.

What Is the Core Value of Blocks?

Blocks organize transactions chronologically and link them via hashes to create an auditable history. The consensus mechanism determines how blocks are produced; confirmation counts measure their security; different chains make trade-offs between scalability and safety. Understanding blocks helps users grasp deposit logic, choose appropriate transaction fees, and confidently verify or track transfers on platforms like Gate.

FAQ

Why Does Block Size Affect Transaction Speed?

Block size limits how many transactions can fit in a single block. Larger blocks accommodate more transactions but may slow down verification and propagation; smaller blocks restrict throughput. Different chains have different designs: Bitcoin’s block size is fixed at 1MB; Ethereum adjusts dynamically—directly impacting network congestion and gas fees.

What Is an Orphan Block and Why Does It Occur?

An orphan block is a valid block that most network nodes reject because it wasn't added to the main chain. If two miners simultaneously discover blocks, different network segments may temporarily follow different chains. Eventually, only the longest chain survives; rejected blocks become orphans. This is normal in blockchain networks and doesn’t affect final transaction confirmation.

Can Block Timestamps Be Manipulated?

In theory, miners can set block timestamps but there are strict constraints: timestamps must exceed those of previous blocks but cannot be too far ahead of network time; otherwise, nodes will reject them. This balances flexibility with security to prevent malicious tampering with blockchain history.

What Happens If a Block Is Invalid or Fails?

Invalid blocks are rejected by all network nodes and not added to the chain. Miners simply continue working from the last valid block. This makes blockchains highly tamper-resistant—altering history would require recalculating all subsequent blocks at immense cost. Invalid blocks do not affect already confirmed transactions.

Can My Transaction Be Rolled Back After Confirmation?

There’s a very small chance immediately after your transaction is included in a new block—it may be rolled back due to chain reorganizations (when competing chains resolve). However, as confirmations increase, this probability drops exponentially—six confirmations on Bitcoin or similar numbers on Ethereum are generally considered final. Gate will typically credit deposits only after sufficient confirmations, so users need not worry excessively.