A batch of ordered transactions plus information needed to check it.
LET’S PICTURE IT
A notebook page has both its entries and a heading that says where it belongs. A block similarly carries transactions and identifying information.
SEE IT FOR YOURSELF
Link blocks, then see what an edit breaksStep 1 / 4
The first toy block records Maya sending Leo three units. A1 is an illustrative fingerprint label, not a real cryptographic digest.
The first toy block records Maya sending Leo three units. A1 is an illustrative fingerprint label, not a real cryptographic digest.Block two stores a reference to A1. A new page is connected to the prior page through its fingerprint.Block three refers to B2. The linked history now has three pages, each building on the previous one.Editing block one changes its toy fingerprint to X9. Block two still refers to A1, so its parent link is invalid and the downstream continuation needs revalidation.
Animated local teaching model. No wallet, RPC or live blockchain data. Some labels and hashes are abbreviated for readability.
A batch of updates
A block groups transactions into an ordered unit. Applying its accepted transactions to the previous state produces a new state. A block can be valid even if it contains no ordinary user transactions.
A header describes the batch
A block header includes information such as the parent reference and commitments to data. A commitment is a compact fingerprint tied to that data. Ethereum’s actual block format has additional execution and consensus details.
A parent gives it a place
The parent hash identifies the block before it in the chain. This is why a block is part of a sequence rather than an isolated bundle. Block numbers describe position but do not uniquely identify every possible block at that height.
Checking beats trusting
A node verifies that the block’s contents and state transition satisfy the rules. A website displaying a green badge is just a view of data; the protocol’s checks are what determine validity. Follow the hash links next.
QUICK CHECK · NO PRESSURE
Can competing blocks have the same block number?
Different candidate blocks can exist at the same height. Their hashes distinguish them.