What is Block Header?

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A block header is used to recognize a particular block among the entire blocks on a blockchain. It is hashed continually to create proof of work for mining rewards. A blockchain consists of various blocks that store data on transactions that occur on a blockchain network. Each of the blocks contains a unique header that differentiates it from other blocks.

The block header serves as a summary of the rest of the block. It’s made up of metadata like the time and difficulty when the block was mined, the block hash of previous blocks, the Merkle root of the included transactions, and the nonce. 

Miners hash a block header to make the block valid. This is a lot more efficient than hashing the entirety of the block, which can be made up of thousands of transactions. 

Block Header Components

Timestamp :

Timestamp is a component of the block header that proves that the particular block is used at an instance of a time. It’s also used to verify the authenticity of any block.

Version :

It states the version that the particular block is using. The versions of Blockchain include the following:

  • Blockchain Version 1.0 (cryptocurrency)- It uses a public ledger to store the data, for example, Bitcoin.
  • Blockchain Version 2.0 (smart Contract)- It involves the use of self-executing programs, for example, Ethereum.
  • Blockchain Version 3.0 (DAPPS)- It is used to create decentralized structures and apps.
  • Blockchain Version 4.0 (Blockchain for Industry)- It is used to create a scalable, affordable blockchain network that can be used by institutions.

Merkle Root :

A Merkle root uses mathematical formulas to check if the data is not corrupted, hacked, or manipulated. For instance, if a block has 10 transactions, to identify that block we need 10 transactions to combine and form one Hash Value, so it uses the concept of the binary tree to create the hash of the block and that value is called the Merkle Root.

Difficulty Target :

It indicates the difficulty and the computation power required to mine the network. 

Nonce :

It is a 32-bit number that blockchain miners are solving for., it takes almost 10 times to find out the correct nonce. 

Previous Hash :

As Blockchain is a collection of several interconnected blocks, a block stores the hashed value of the previous block. The first block in the blockchain is called the Genesis Block and has no previous block hash value.