A blockchain is a shared record that many computers keep in step, where past entries can't be quietly changed. It was first described in the 2008 Bitcoin paper, and today it runs cryptocurrencies, tokens and a number of business networks. This guide explains how a blockchain works in plain terms, when it is the right tool and when it isn't, and the steps to implement one in 2026.
A blockchain is a ledger split into blocks, each linked to the one before it by a cryptographic hash and copied across many independent computers, which agree on new entries through a consensus method such as proof of stake. It is worth using when several parties who don't fully trust each other must share one record and no single operator should control it. If one trusted organisation runs the system, a normal database with an audit log is cheaper and faster. To implement one, pick a public chain or a permissioned ledger, write and audit the smart contracts, and host the website and back end like any other application.
1. What a blockchain is
At its core, a blockchain is a ledger: a list of transactions or records, in order. Three things make it different from an ordinary database:
- It is shared. Many computers, called nodes, each hold a full copy and check every new entry.
- It is append-only. New records are added in blocks at the end; old ones are not edited or deleted.
- It is tamper-evident. Each block includes a fingerprint (hash) of the previous block, so changing an old record breaks every link after it and the other nodes reject the change.
Because no single computer holds the master copy, no single operator can rewrite history or shut the ledger down on its own.
2. How it works, step by step
- A transaction is created and signed.The sender signs it with a private key that only they hold. Anyone can check the signature with the matching public key.
- The network shares it.The transaction is passed between nodes, which check that it is valid, for example that the sender has the funds.
- A block is proposed.One node bundles valid transactions into a block, with the hash of the previous block.
- The network agrees.The nodes run a consensus method to accept the block, so that everyone ends up with the same history.
- The block is added.Every node appends it to its copy. After enough further blocks, reversing it becomes practically impossible.
3. Consensus: how strangers agree
Consensus is the rule that decides which block comes next when nobody is in charge.
| Method | How a block is chosen | Where it is used |
|---|---|---|
| Proof of work | Nodes race to solve a costly puzzle; the winner adds the block | Bitcoin |
| Proof of stake | Validators lock up coins as a deposit and are chosen to propose blocks; cheating costs them the deposit | Ethereum since 2022, most newer public chains |
| Byzantine fault tolerant (BFT) voting | A known set of validators vote; a block needs a large majority | Cosmos chains, many permissioned networks |
| Crash fault tolerant ordering (Raft) | A known ordering service puts transactions in order | Hyperledger Fabric networks |
Older guides say an attacker needs "more than 50% of the computing power". That is true for proof of work. On proof-of-stake chains the equivalent is controlling a large share of the staked coins, and on permissioned ledgers it means corrupting enough of the known organisations.
Ethereum's move from proof of work to proof of stake in 2022 cut its energy use by more than 99%, which answered the main environmental criticism of that chain.
4. Public chains and permissioned ledgers
- Public chains such as Bitcoin, Ethereum and its Layer 2 networks, and Solana are open to anyone. Every transaction pays a fee and every record is visible to all. They suit tokens, payments and applications where users should not have to trust you.
- Permissioned ledgers such as Hyperledger Fabric and Corda are run by a known group of organisations. Access is controlled, data can be private to the parties involved, and there is usually no cryptocurrency. They suit supply chains, trade finance and records shared between companies.
Smart contracts are programs stored on the chain that run automatically when their conditions are met, for example releasing a payment when goods are marked as delivered. A bug in a smart contract can't simply be patched once it is deployed, so contracts are tested and audited carefully.
5. When a blockchain helps, and when it doesn't
- Several organisations must share one record and none should control it
- A permanent, verifiable history matters more than speed
- Participants need to check records without trusting a central operator
- Assets or rights are transferred between parties who don't know each other
- One trusted organisation runs the system anyway
- Data must be edited or deleted later, for example for privacy law
- You need thousands of fast, cheap writes per second
- The data is private and only one team uses it
If your participants already trust one operator, a conventional database with an audit log gives the same benefits at a fraction of the cost. Personal data is a particular concern: under India's Digital Personal Data Protection Act 2023 and similar laws, people can ask for their data to be erased, which an append-only public ledger can't do. Keep personal data off-chain and store only references or hashes on the chain.
6. Implementing a blockchain solution
- Prove the use case.Write down who the participants are, what they share and why a database is not enough. If you can't answer the last point, stop here.
- Choose the model.A public chain (usually an Ethereum Layer 2 for new projects) for open, token-based applications; a permissioned ledger such as Hyperledger Fabric or Corda for a business network.
- Decide what goes on-chain.Put only what must be shared and verified on the chain; keep files, personal data and bulky records in ordinary storage.
- Write and test the smart contracts.Use current tools such as Foundry or Hardhat for Solidity, reuse audited libraries such as OpenZeppelin Contracts, and test thoroughly on a test network.
- Get an independent auditbefore contracts that hold money or valuable rights go live.
- Build the application around it.A website or app, a back end that reads the chain through an RPC provider or your own node, and wallet or key management for users.
- Plan operations.Key storage, monitoring, contract upgrades and incident response, and how participants join or leave a permissioned network.
Older tutorials often start with Truffle, Ganache or Hyperledger Composer; all three are retired. Our guide exploring the tech stacks for building blockchain applications lists the current tools for each platform, and building a blockchain-based supply chain system is a worked example.
Whoever holds a private key controls the assets and contract permissions behind it, and a lost key can't be reset. Never store deployer or admin keys on a web server or in a Git repository; use a hardware wallet or a secured CI secret.
7. A note for Indian businesses
Building software on blockchain technology is not restricted in India. Cryptocurrencies and other virtual digital assets are treated separately for tax: since 2022, gains are taxed at a flat 30% (plus cess) and 1% TDS applies to many transfers. This is general information, not legal or tax advice; the rules in this area change, so check with a chartered accountant before you issue or accept tokens.
8. Running this on Domain India
Only the smart contracts run on the blockchain. Everything else is ordinary software you host yourself.
- Website and dApp front ends are usually static files. Upload the built site to any Domain India shared hosting plan; free SSL is included.
- Back-end services such as APIs and indexers run on the App Platform, where Node.js apps are detected automatically and other stacks run from a Dockerfile.
- Blockchain nodes and permissioned networks need your own server. A Domain India VPS gives you root access and is self-managed; check the node software's storage requirements before you order, because full nodes for major chains need a lot of disk space.
Shared hosting is not suitable for running nodes. Prices on the cards are live Domain India list prices and exclude 18% GST.
- 512 MB RAM per app
- 1 vCPU
- 5 GB NVMe SSD
- PostgreSQL Database
- 1 vCPU
- 2 GB DDR4 RAM
- 64 GB NVMe SSD Storage
- 2 TB Monthly Bandwidth
Frequently asked questions
What is blockchain technology in simple words?
A blockchain is a shared record kept by many computers at once. New entries are added in blocks, each linked to the previous one by a cryptographic hash, so past entries can't be changed without everyone noticing.
Is blockchain the same as Bitcoin?
No. Bitcoin is one application built on a blockchain. The same technology runs other cryptocurrencies, tokens, smart contracts and private business ledgers such as Hyperledger Fabric.
What is the difference between proof of work and proof of stake?
In proof of work, computers compete to solve a costly puzzle to add each block, which uses a lot of electricity. In proof of stake, validators lock up coins as a deposit and are chosen to add blocks, losing the deposit if they cheat. Ethereum switched to proof of stake in 2022.
Does my business need a blockchain?
Only if several parties who don't fully trust each other must share one record that no single organisation controls. If one trusted operator runs the system, a normal database with an audit log is cheaper and faster.
Can data on a blockchain be deleted?
Not on a public blockchain; records are permanent and visible to everyone. Keep personal data off the chain and store only references or hashes, so that you can still meet privacy obligations.
Can I host a blockchain application on shared hosting?
You can host its website or static front end on shared hosting. Back-end services need an app platform or VPS, and blockchain nodes need a server with large storage.
Ready to build? Host your front end on cPanel hosting, run your API on the App Platform, or compare VPS plans for a node. Not sure which fits? Open a support ticket and describe your project.
Run Node.js back ends automatically, or any other stack from a Dockerfile, with SSL included.
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