Blockchain Blocks Explained: How Blocks Are Added To A Blockchain

By Ezoh Joseph
12 Min Read

In recent years blockchain technology has emerged as a prominent technology adopted by various institutions across the globe. With use cases ranging from data storage and management this technology has become a revolution cutting across all aspects of life. But how does this complex system develop and change on its own? The answer revolves around adding blocks to the chain in a very detailed manner. 

Blockchain technology is a distributed ledger scheme that ensures safe, immutable, and transparent data keeping. At the heart of this technology lies the notion of blocks which constitutes a bundle of confirmed transactions, appended into a chain. 

What Is A Blockchain?

A blockchain is a distributed and decentralized digital ledger of transactions, stored on different computers within a network environment. Introduced as Blockchain Version 1.0 by Hal Finney in the year 2005, the technology has evolved to Blockchain 2.0 (Smart Contracts) and the current Blockchain 3.0 (dApps). This technology is composed of blocks that make up a string or a chain whose elements are lists of transactions. The key features of any blockchain network include:


A blockchain is distributed, unlike a normal centralized system where only one controlling authority controls the ledger. As such, there is no single entity that can take over the whole chain of blocks, thus ensuring censorship resistance that no one can do a change on it.

Distributed Ledger

All the participants in this network have their own ledgers or records of transactions. The blockchain is distributed among each participant, and new information spreads throughout the system in real time.


Transactions within the blockchain network are organized into blocks. Each of these blocks contain a record of the previous transaction block, thus forming a chain of information. This mechanism of chaining guarantees the correctness with regard to all past transactions. After the addition of a block on a chain, it becomes nearly impossible to alter it which ensures enough safety.

Consensus Mechanism

For a new block to be added to the blockchain, there should be consensus among the network members on the legitimacy of the transactions in that block. To reach an agreement with no central authority, many consensus mechanisms have been developed for example, Proof-of-Work used by Bitcoin and Proof-of-stake utilized by Ethereum.

To understand more on consensus mechanism, and get the difference between proof-of-work and proof-of-stake mechanisms read this insightful article

In the past years recording and tracking transactions was a process done only by the financial institutions. Auditing these transactions would take some time and was only for the few select parties hence making them centralized.

Blockchain technology came to revolutionize transactions and provide transparency in record keeping, easily facilitating sharing within networks. Transactions conducted using the technology are executed and automated by smart contracts hence eliminating third-party institutions such as banks. Furthermore once a transaction is added in the ledger, no one can do a change on it. This is because there is no centralized master copy of the blockchain as the information is validated by other nodes in the network.

How Does A Blockchain Work?

how blockchain works

A blockchain operates on a network of distributed and decentralized computers(nodes). It utilizes cryptography and consensus mechanism techniques to ensure immutability, transparency and safety of data stored. Under cryptography, blockchain utilizes two types of keys: a public key and a private key to create a solid form of digital identity.

For an introduction to public and private keys, their differences and how they work. Read this comprehensive guide

Like a database, the blockchain contains programs known as scripts which conduct tasks assigned to them. Once a transaction information is added to it, blockchain picks it up and adds it into a block. When the block is full the information is channeled through an encryption process and comes out in the form of a cryptographic hash which serves as a transaction’s footprint.

After this the hash is added into the next block header and encrypted together with all the other information contained in the current block. This gives rise to a chain of interlinked blocks.

What Is A Block In Blockchain?

The word blockchain is an abbreviation of two words, ‘block’ and ‘chain’. In the realm of blockchain technology, a block is a collection of transactions brought together and added into the network as a single unit. These blocks are linked together in a linear and sequential manner to form a chain- duly referred to as blockchain.

Each block within the blockchain network, has the following key components:

Block Header

Block header constitutes information about the current block such as the date of the block creation and a reference to the previous block within the chain. The reference is achieved by using the cryptographic hash of the previous block, generating an extended and unbroken chain.


A block consists of a sequence of transactions which are an array of data activity from the entire network of blockchain. These could be transactions from asset transfer like cryptocurrency, smart contracts execution among others depending on the blockchain’s purpose.

A nonce

A nonce(number used once), is an encrypted number included in blocks within blockchains utilizing proof-of-work consensus mechanism. Miners use this number to identify a block and add it to the chain after certain conditions are met.


Each block generates its special cryptographic hash depending on the block’s data, that is, transactions and the previous block’s hash. This hexadecimal number serves as a digital fingerprint for the entire block, ensuring trust of the entire blockchain. Additionally, this component helps to ensure that no single block can be altered without affecting those that follow.

Adding Blocks To A Blockchain

Any new block in a blockchain is added by hashing the transactions sent into the network by users. 

Once a transaction is initiated by a user it is authenticated and verified for accuracy by the network’s nodes. Such validation criteria are dependent upon the type of consensus mechanism used in that particular blockchain network. Once validated, the  transaction is arranged in one block with a hash number as well as reference of the preceding block within the chain. Nodes within this network confirm the legitimacy of the transaction in the proposed block and the order in which they will be added to the blockchain.

Read this guide to understand how blockchain validates transactions added onto them and ensure that they are legit and executed correctly  via block confirmation

After nodes approval, miners in the case of proof-of-work mechanism compete to add the block. This process known as mining involves solving complex hash puzzles. Then, the miner who solves the problem first sends a message to the network notifying others of his/her success to provide a solution. Once the solution is accepted and approved by other nodes, then a new block is added and the winner miner gets a reward.

The new block is assigned a unique hash which links it with the preceding one to form a chain. It is then distributed within the network, whereby every node updates its copy for the blockchain to incorporate it. This linking of information by every node forms an interminable and a public chain making it nearly impossible to tamper with.

However, not all blockchain networks follow this procedure when adding a block to a chain. For example Ethereum network which utilizes proof-of-stake consensus mechanism chooses a validator to add a block based on the number of tokens held. The more tokens a validator holds, the more likely they are to be the validator for a given transaction. This makes transactions quick and efficient with less energy consumption as compared to Bitcoin transactions.

The Future of Blockchain Uses

Blockchain holds an enormous potential as it continues to evolve and get implementation across various real world sectors. Currently there are thousands of cryptocurrencies running under the blockchain network. And as they continue to expand adoption of this technology, they pursue new ways to improve it. Blockchain networks like Bitcoin and Ethereum are integrating  new ways to be more efficient, secure and cost effective than before.

Additionally, sectors like healthcare, banking, voting systems, governance, digital asset ownership, supply chain management among others present an untapped potential for this technology. Indeed the next world revolution is based upon blockchain use to make business and government operations more accurate, efficient, secure, and cheap, with fewer middlemen. The question at hand is not if these sectors will uphold the technology but it is when? Today we see tokenization of real world assets and an increase of NFTs  but the next decade and more to come will document the real adoption of this technology.

To understand more about the future of blockchain technology, opportunities and challenges it holds for developers, read this detailed article


The process of adding blocks to a blockchain network, though complex, can be organized into several stages to ensure safety, immutability, and transparency in data keeping. Blocks are a crucial element within this chain and miners commit themselves in solving complex mathematical puzzles, to include new ones into the chain. Although their validity is mostly determined by the utilized consensus mechanism this whole process highlights the trustworthiness and reliability of this technology.

The future looks bright for blockchain as it is set to bring changes in a range of fields like finance, supply chain management, health care, and governance. However, the power of the blockchain doesn’t lie solely in its capability to securely register deals. But it also has the power to reshape how trust is created, businesses are conducted and humans communicate in the modern digital world. The use of blocks in the building of a chain is not only about a technical process but rather it is transforming the future digital framework with decentralization, transparency, and immutability.

Meet Ezoh Joseph, a beacon writer in the often complex and ever-evolving landscape of cryptocurrencies, blockchain technology, and decentralized finance. Translating the complexities of the Web3 technology he is able to transform tech into accessible narratives.