Essential Knowledge for Developers Venturing into Blockchain

When you first encounter blockchain, you’ll likely come across concepts like decentralization, distributed ledgers, consensus algorithms, tokenomics, smart contracts, transactions, and more. Indeed, having a solid grasp of these ideas—and understanding how they all fit together—is crucial if you want to fully comprehend blockchain technology.

However, in this piece, I’d like to focus more on the knowledge developers need to actually build or integrate with blockchain projects.

“When you’re faced with the situation of having to develop on or connect to a blockchain, what are the minimum essentials you need to know?”

The following sections aim to give you a broad overview.

In typical web or mobile applications, the flow usually looks like this

• Client (Web/App) → Server (Backend) → Database (Data Storage)

• A central server handles most of the logic, and data is stored and retrieved from a database.

Blockchain takes a very different approach:

• Multiple nodes in the blockchain network all share the same ledger (data).

• There’s no central server; instead, these nodes record new transactions via a consensus mechanism.

• Anyone can run a node or access the data, and even if one node goes down, the network as a whole continues to function.

The key point here is that it’s the entire network, not a single server or database, that manages and verifies the data. As a result, changes (transactions) are handled very carefully, ensuring immutability and transparency.

Blockchain isn’t really a direct replacement for traditional RDB or NoSQL databases. Rather, it’s a specialized data structure designed for transparency and immutability.

• When you add data (write) via a transaction, it must pass network validation and be shared by all nodes.

• Once recorded, it’s very hard to change or delete.

• Large amounts of data can be expensive (due to gas fees), and on-chain storage is not highly efficient.

In practical implementations, crucial data—like ownership or transaction records—goes on-chain, while secondary data (images, logs, metadata, etc.) is stored off-chain (IPFS or a traditional database), then linked via hashes or references.

• Event-based history: When a contract’s state changes, it emits events, which can be indexed for easy retrieval.

• Indexing solutions (e.g., The Graph): They gather events from the blockchain and store them in a more query-friendly form—like a database—for use by your dApp.

The main takeaway is that blockchains are designed for trust and immutability, not for dumping and querying massive data. Often, you run a separate indexer to convert “events → DB,” boosting efficiency and convenience.

We noted that a node plays the role of both server and database in a blockchain. But must you operate your own node to interact with a blockchain? Not necessarily.

1) Running your own node

• For major chains like Ethereum, running a full node requires hundreds of gigabytes of storage and a stable network connection.

• Costs, maintenance, and DevOps expertise can be significant.

• However, if you need large-scale on-chain data collection—like analyzing high-frequency transactions, running trading bots, or conducting big data research—operating your own node can be advantageous.

2) Using external node services

• Services like Infura, Alchemy, or QuickNode provide RPC endpoints (URLs), giving you direct access to blockchain functions (submitting transactions, querying data, etc.) without managing infrastructure yourself.

• Many dApp projects rely on these to get up and running quickly.

3) Local development nodes

• Tools like Ganache and Hardhat Network let you spin up a “fake blockchain” locally.

• Perfect for testing, learning, or personal side projects.

In short, you don’t always need to run your own node. You can decide based on your project’s traffic, data needs, and operational resources.

In traditional web or mobile apps, we typically use ID/PW, JWT, OAuth, etc. for user authentication.
In blockchain dApps, however, wallets (like MetaMask, Trust Wallet, etc.) handle the concept of “authentication.”

• A wallet stores the user’s private key, enabling them to sign transactions.

• Authentication Flow:

  1. The dApp (client) requests a signature for a specific message (or transaction).

  2. The user’s wallet signs it with their private key and returns the signature.

  3. The dApp verifies that the public key (wallet address) and the signature match, confirming the user’s ownership of that address.

Security Implications

• There is no central server storing your password; instead, users themselves manage their private keys.

• If a private key is lost or compromised, there’s almost no way to recover it (no “reset password” option).

• Familiar features like MFA or password recovery aren’t typically available.

To address these challenges, various solutions are emerging, such as:

• Account Abstraction (AA): where the wallet is a smart contract account, enabling features like social recovery or fee subsidization.

• Seedless logins, smart contract wallets, and other innovations to improve security and user experience.

A blockchain isn’t just a ledger of data—it allows you to run code (program logic) directly on-chain. We call this code a smart contract.

• Immutable Code
  Once deployed to the blockchain, the code is difficult (or sometimes impossible) to modify.
  If a bug is discovered in the logic, patching can be extremely difficult. Thorough testing and security audits are critical.

• Decentralized Trust
  Unlike a scenario where you host code on a private server and claim “this is how it works,”
  a blockchain-based contract is openly deployed on the network. Anyone can review the logic and see exactly how it’s executed.
  (For example, by plugging the contract address into a block explorer to verify the source code and transaction history.)

• Deployment Process
  You write code in languages like Solidity or Vyper (for Ethereum), compile it, then send a deploy transaction.
  The contract is assigned a unique address (like a wallet address starting with 0x).
  Once deployed, anyone can interact with it by sending transaction calls to that address. The network executes the logic and records the results on-chain.

Some of the most prominent uses of smart contracts include tokens (ERC-20), NFTs (ERC-721), and DeFi protocols.

• ERC-20 (Tokens)
  The standard interface for creating interoperable tokens on Ethereum.
  If you implement functions like balanceOf, transfer, and approve, wallets and exchanges automatically recognize your token and enable features like balance checks and transfers.

• ERC-721 (NFTs)
  A standard for non-fungible tokens.
  Each token has a unique ID, allowing ownership of each item to be distinctly tracked—common for artwork, profile pictures, in-game items, memberships, etc.

• DeFi (Decentralized Finance)
  Smart contracts implementing financial services such as lending, staking, swaps, or liquidity pools.
  Anyone can use them under the same conditions, without a central authority.

Below is a simple example illustrating how an ERC-20 contract might work. (In practice, the standard includes events and more functions, but this showcases the core logic.)

pragma solidity ^0.8.0;
contract MyToken {
    mapping(address => uint256) private _balances;
    string public name = "MyToken";
    string public symbol = "MTK";
    uint8 public decimals = 18;
    uint256 public totalSupply;
    constructor(uint256 initialSupply) {
        _balances[msg.sender] = initialSupply;
        totalSupply = initialSupply;
    }
    function balanceOf(address account) external view returns (uint256) {
        return _balances[account];
    }
    function transfer(address to, uint256 amount) external returns (bool) {
        require(_balances[msg.sender] >= amount, "Not enough balance");
        _balances[msg.sender] -= amount;
        _balances[to] += amount;
        return true;
    }
}

You’ll see it tracks balances in a mapping and uses a transfer function to update them. ERC-721 (NFT) follows a similar model, except each token ID is unique and individually tracked.

In essence, “tokens” or “NFTs” are simply interfaces provided by smart contracts.

• Transaction: Any operation that changes blockchain state (like sending funds or calling a contract).

• Gas Fee: The cost paid to the network (in ETH, MATIC, BNB, etc., depending on the chain) for processing each transaction.

As a developer, consider:

• UX

  • Every time a user sends a transaction, they must confirm it in their wallet and pay a gas fee.

  • Frequent transaction prompts may hurt usability. You usually want to design so that on-chain actions happen only when truly necessary.

• Cost

  • Large transaction volumes can drive gas costs up significantly.

  • Each chain has different fees and throughput, so choosing the right chain can greatly affect the business model.

Once you deploy a smart contract, how do you actually call its functions or access its variables?
Think of how REST APIs require you to know the endpoints, parameters, and methods.
Similarly, a contract needs a description of “which functions exist and what parameters/return types they use.”
That’s exactly what the ABI (Application Binary Interface) is for.

Without the ABI, simply knowing the contract’s address tells you nothing about how to interact with its internal functions. Hence, to use a deployed contract, you must have its ABI.

Example
Suppose an ERC-20 token contract has balanceOf and transfer as part of its ABI:

[
  {
    "type": "function",
    "name": "balanceOf",
    "inputs": [
      { "name": "account", "type": "address" }
    ],
    "outputs": [
      { "type": "uint256" }
    ]
  },
  {
    "type": "function",
    "name": "transfer",
    "inputs": [
      { "name": "to", "type": "address" },
      { "name": "amount", "type": "uint256" }
    ],
    "outputs": [
      { "type": "bool" }
    ]
  }
]

• balanceOf: takes an address and returns a uint256 balance

• transfer: takes a to address and an amount (uint256), returns a bool indicating success

Using this ABI, you can call these contract functions. For instance, in ethers.js:

import { ethers } from "ethers";
import MyTokenABI from "./MyToken.json"; // Precompiled contract ABI
// Deployed contract address
const tokenAddress = "0x123456789ABCDEF...";
// Create contract instance with address + ABI
const tokenContract = new ethers.Contract(tokenAddress, MyTokenABI, signer);
// Example: check balance
const balance = await tokenContract.balanceOf("0xABCD1234...");
console.log(balance.toString());
// Example: transfer tokens
await tokenContract.transfer("0xEFGH5678...", 100);

ABI is effectively the “spec sheet” for function signatures: which parameters they require and what they return. If you’re curious how the actual function call process works, it involves:

1. Calculating a 4-byte function selector (via Keccak-256 of the function signature),

2. Encoding parameters into call data,

3. Sending it to the EVM, which uses the selector + encoded arguments to execute the correct function.

For more details on the encoding rules, check the official documentation.

• Security

  • Once deployed, a smart contract is hard to patch. A single bug can lead to massive loss of funds.

  • Projects dealing with large amounts of value usually invest in professional security audits.

• Cost (Gas Fees)

  • A large number of transactions can become expensive and inconvenient for users.

  • Decide how to handle those costs (do users pay or does the platform subsidize?).

• UX

  • Everything from installing a wallet to paying gas and waiting for confirmations differs from typical web apps.

  • Often, it’s best to limit on-chain transactions to only what’s absolutely necessary, lowering user friction.

Ethereum, Polygon, BNB Chain, Avalanche, Solana… the list continues to grow. Each chain has its own strengths and weaknesses, so choose based on your project’s needs:

• Gas Fees & Throughput

  • Ethereum offers robust security and a vast ecosystem but has relatively high gas fees.

  • Polygon (a Layer 2 solution) provides cheaper, faster transactions, but might involve bridging assets.

• Ecosystem (Wallets, DEX, NFT marketplaces, etc.)

  • A chain that users and developers already widely adopt can reduce friction (e.g., MetaMask support, established markets, etc.).

• Security & Decentralization

  • A chain with fewer nodes or weaker consensus might pose risks to trust and reliability.

Ultimately, factors like gas fees, processing speed, security, and ecosystem support should guide your decision. Your project’s size, goals, and user base will shape the best choice.

There’s no need to dive deeply into consensus algorithms, tokenomics, sidechains, or Layer 2 solutions right away. A good starting point is to experiment on a testnet, deploy a basic smart contract, and send transactions from a wallet to get familiar with the flow. This hands-on approach will give you a taste of the UX and security challenges inherent in blockchain-based applications. Later, you can dive deeper into more advanced topics as your project demands.

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