The central element of every cryptocurrency is a public ledger called the called blockchain, which links blocks together.

Since the blocks in the chain are ordered, the complete transaction history is held in the blockchain. Subsequent blocks in the blockchain have increasing heights that differ by one.

Blocks are stored on a database as permanent medium. NEM calls the first block in the chain the nemesis block.

NEM blocks complete every 15 seconds, making transactions confirm quickly enough for everyday use.


Configuration parameters are editable . Public network configuration may differ.

Block creation

Blocks are created by accounts. The process of creating new blocks is called harvesting. The harvesting account - called the harvester - gets the fees for the transactions in the block. This gives the harvester an incentive to add as many transactions to the block as possible.


Blocks are composed of the following properties:


The block signature. This is generated by the signer and can be used to validate that the block data was not modified by a node.


The public key of the harvester of the block as a hexadecimal number.


The version of the block. The higher byte represents the network identifier.

Block version Description High byte
MAIN_NET Public main network 0x68
TEST_NET Public test network 0x98
MIJIN Private network 0x60
MIJIN_TEST Private test network 0x90


The type of the block.

Block type High byte Low byte Decimal
Nemesis Block 0x80 0x43 32835
Block 0x81 0x43 33091


The height of the blockchain. Each blockchain has a unique height. Subsequent blocks differ in height by 1.


The number of seconds elapsed since the creation of the nemesis block.

Previous block hash

The sha3-256 hash of the last block as an hexadecimal string.

Block transaction hash

The transactions included in a block are hashed forming a Merkle Tree. The root of the tree summarizes them.