FOLLOW THE MECHANISM
- 1Candidate
A producer selects and orders transactions.
- 2Commitments
The block records its parent and data fingerprints.
- 3Verification
Other nodes check the complete transition.
- 4Selection
Consensus determines which valid history is followed.
A conceptual sequence. Real implementations can add steps, intermediaries, and conditions.
A batch with a parent
A block contains or commits to transaction data and identifies a previous block. The precise header and body differ across protocols. A parent link locates the block in a history, while transaction commitments make substitutions detectable. Blocks may contain fewer transactions than their capacity allows, including very few ordinary transfers. The existence of a block is not evidence of a particular level of economic activity.
Order changes what is possible
Transactions execute against the state left by earlier transactions. One instruction may fund an account used by the next, consume an output that another instruction wants, or change the price in a liquidity pool. Block order is consequently part of the economic mechanism. A producer cannot generally include any arbitrary combination of individually plausible instructions and expect the resulting sequence to satisfy the network’s rules.
Capacity is a constrained resource
Networks limit block resource usage to bound the work required for validation and propagation. Bitcoin uses weight-related limits; Ethereum meters execution using gas and has additional resource rules. Fees help allocate scarce inclusion capacity, but paying a high fee cannot authorize an invalid action. Increasing capacity can reduce some bottlenecks while raising hardware, bandwidth or state-growth demands on participants who independently verify the system.
Accepted now is not always final
Two producers can create competing valid blocks that share a parent. The protocol’s fork-choice mechanism determines which branch nodes follow. A transaction in a displaced block may return to pending status or conflict with another accepted transaction. Hash links make the relationship visible; finality mechanisms determine how confidence in that relationship develops. Block height alone is not a universal measure of safety across different networks.
MAKE IT CONCRETE
Order determines spendability
Suppose account A begins with zero example units. Transaction one pays A five units; transaction two asks A to send three units onward. In an account-based model the second instruction can succeed after the first, assuming authorization and fees are valid. Reversing the order may make it fail. The block is an ordered computation, not an unordered envelope.
FAILURE PATHS & COMMON MISREADINGS
Where the model can break
- A block explorer’s display is a presentation of chain data, not a separate consensus authority.
- More transactions in one block can also mean more work for verifiers.
KEEP EXPLORING