WORKING DEFINITION
A block contains one or more transactions.an ordered set of transactions. It is cryptographically linked to the preceding block, and in turn it is linked to be subsequent blocks. The first block in such a chain of blocks is called the genesis block. Blocks are created by the ordering service, and then validated and committed by peers.
https://hyperledger-fabric.readthedocs.io/en/latest/glossary.html
A block contains one or more transactions. The contents of the block are not encrypted in the blockchain. A block, in general, contains valid and invalid transactions. However invalid transactions have no effect on the State.
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