What is a block in blockchain?

What is a block in blockchain?

Earlier we already talked about blockchain technology and many times in our reviews you may have come across such words as "block", "node", "node" and most likely you already know what we are talking about. But if the meaning of these words is still a mystery for you or you want to get into details - this review is for you.

What is a block in Blockchain?

Blocks are records that together form a blockchain. In the world of cryptocurrency, blocks are like the pages of a book, and the whole book is the blockchain. A block is a file that holds immutable data related to the network. They hold all records of valid (validated or validated) cryptocurrency transactions. They are hashed and encoded into a hash tree or Merkle tree.

The first block in the blockchain is the Genesis block. It is the only one that has no data in the previous block, because there is nothing in front of it. All other blocks have a cryptographic hash, which is obtained from the previous block. Each block replicates all the data from the previous blocks. Instead of having a central register with the data of the whole system, each block in the whole chain has all the data. In other words, blockchains use a distributed register system rather than a centralized one.

What is a Block Candidate

A candidate block is a block that attempts to mine a mining node (miner) in order to receive a reward. Thus, a candidate block can be described as a temporary block that will either be verified and confirmed or discarded by the network. Miners compete with each other to verify the next block and add it to the chain, but they must first create a candidate block to compete.

Candidate blocks are formed by miners by collecting and organizing multiple unconfirmed transactions from the memory pool. The transactions are then hashed to form a Merkle tree structure, which will eventually create a Merkle root (root or master hash). This is a single hash that represents all previous hashes of that tree and therefore all transactions that have been included in that particular block.

The master hash, along with the hash of the previous block and a random number that can only be used once (nonce), is placed in the block header. The block header is then hashed by the miner, generating an output based on these components (the root hash, the hash of the previous block and the one-time number), as well as several other elements. The result is a block hash and will serve as a unique identifier for the newly generated block (candidate block).

To be valid, the output (block hash) must start with a certain number of zeros (less than the target value defined by the protocol). This means that the mining process is based on multiple attempts (trial and error), as the data mining nodes have to perform multiple hashing functions with different nonce values until eventually a valid block hash is created. The resulting block hash proves that the miner has done its job (hence the proof-of-work consensus protocol).

After the miner finds a valid hash block, its candidate block will be broadcast to the rest of the network to verify authenticity. If all is well, the candidate block will be written to the blockchain. At this point, each verifying node updates its copy of the blockchain data to reflect the last mined block, and the miner receives its reward.

What are network nodes

A node (node) is a mechanism in a network with a chain of blocks, which is essentially the basis of blockchain functioning. Nodes belong to a widespread network and perform a variety of tasks.

A node can be any working electronic device that has access to the Internet and, accordingly, its own static personal IP address. The function of a node is to be a mainstay of the network, that is, to store a copy of block information. Each digital currency has personal nodes that interact only with data from its blocks.

Nodes are fragments of a larger data architecture called a blockchain. As holders of nodes give access to their computing resources to store and revise transactions, they are rewarded for doing so (most often in coins of the blockchain's parent currency). This is called mining.

Processing these transactions requires a lot of processing power - which means that the average personal computer is not capable of it. Therefore, those who specialize in mining have to spend a lot of money on hardware such as central processing units (CPUs) or graphics processing units (GPUs) in order to reach the required level.

The productivity required to operate multiple nodes also requires high electricity costs. Therefore, the largest and most profitable mines are located in countries where the cost of electricity is lower, such as the PRC, the UAE, Saudi Arabia, etc.

A node can act as a final or relay station that communicates with other nodes. All nodes have the same right to vote, but not all of them do the same job. Conventionally, they can be divided into full and partial. A full node contains absolutely all information from the blockchain and audits all new transactions. A partial node stores pieces of information and may not take part in processing new transactions. But all nodes within the same blockchain operate on the same consensus protocol in order to maintain interoperability between them. But all nodes within the same network

Why blocks make cryptocurrencies safe

Blockchain is extremely difficult to hack or manipulate. Conducting such a large-scale cyberattack is virtually impossible.

Physical (fiat) money, such as dollars, euros, pounds, and so on, is legal tender, and therefore under the control of a central authority, such as the National Bank. That is, any physical currency is controlled by some single center that holds all the information.

Digital currencies have no such central bank or ledger - each block contains all the data in the system. Consequently, a successful cyberattack requires hacking each block separately, but at the same time, which is extremely difficult.

Creating fake cryptocurrency is much harder than physical cryptocurrency. That's why we can be 100% sure that when we buy bitcoins - we are buying them and not a quality fake.

Wrapping up the review

Given all of the above information, a simple chain can be drawn. There is a node (computer) that processes all existing and new information (candidate block), and after solving the cryptographic problem (finding a valid hash), sends it to other nodes. If other nodes recognize (by consensus protocol) hash of the block-candidate (result of the solution of the problem) as valid - block is created - fixed fixed information page of the ledger.

We tried to explain the concept of "block" in blockchain, its purpose and undeniable usefulness as simply as possible. We hope you found it interesting. That's all for now and see you next time!

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Article posted8/30/2022Article categoryCryptocurrency
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