Picture a blockchain as a shared notebook that a whole network writes into. Rather than adding one line at a time, the network gathers many transactions, checks them against its rules, and writes them all at once as a single page: that page is a block. Each block also carries a short header of housekeeping data, including the time it was created and a fingerprint of the block before it. That backward reference is the glue that turns a pile of separate blocks into an ordered chain.
Different networks fill and seal blocks at different speeds. A new Bitcoin block appears roughly every ten minutes, while many other chains produce one every few seconds. Once a block is added and a few more stack on top of it, undoing it would mean redoing all the work behind every block since, which is why settled transactions are treated as effectively final. As a concrete example, when you send ETH and later see the transfer described as having a number of confirmations, each confirmation is simply another block that has been built on top of the one holding your payment.
Everything inside a block is public on most networks, so anyone can open a block explorer and read exactly which transactions it contains and when it was sealed. Understanding blocks is a useful first step before terms like block reward, consensus and finality make sense.
Key takeaways
- A block packages many verified transactions plus a small header into one record that is added to the chain together.
- Each block references the previous one, and later blocks stacking on top are what make older transactions hard to reverse.
- Block contents are public, so a block explorer lets anyone inspect what a given block holds.
Block — часто задаваемые вопросы
How long does it take to add a new block?
It depends entirely on the network. Bitcoin targets about one block every ten minutes, whereas many other chains aim for a few seconds. The pace is set by the network's rules, not by how busy it happens to be at that moment.
What are block confirmations?
Each confirmation is one more block added after the block that contains your transaction. More confirmations mean more work would be needed to unwind it, which is why services often wait for several before treating a payment as settled.
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