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Web3 & DApp Development Fundamentals · Lesson

What are Smart Contracts?

Learn the definition, purpose, and key characteristics of smart contracts as immutable, self-executing code on the blockchain.

What are Smart Contracts? is a free Web3 & DApp Development Fundamentals lesson on CoddyKit — lesson 2 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Web3 & DApp Development Fundamentals learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Welcome to Smart Contracts!

Imagine a contract that executes itself automatically when certain conditions are met, without any human intervention or third party.

That's essentially what a Smart Contract is! It's a fundamental building block of Web3 and powers many decentralized applications.

Contracts on the Blockchain

Traditional contracts are written in legal language and enforced by courts or institutions. Smart Contracts are different.

They are lines of code stored and run on a blockchain. This code defines rules and executes actions automatically when those rules are met.

Self-Executing Agreements

One of the core ideas is that they are self-executing. Once deployed, they live on the blockchain and run exactly as programmed.

  • No one can stop them.
  • No one can censor them.
  • They don't need a middleman.

Immutability is Key

Smart Contracts are immutable. This means once a contract is deployed to the blockchain, its code cannot be changed or updated.

This immutability ensures trust and predictability. You know exactly how it will behave because its rules are set in stone.

Transparency for All

Another key characteristic is transparency. The code of a Smart Contract is publicly visible on the blockchain.

Anyone can inspect the code to verify its logic and ensure it does what it claims. This openness fosters trust among participants.

Decentralized Logic

Smart Contracts run on a decentralized network of computers (the blockchain), not on a single server controlled by one entity.

This decentralization makes them resistant to single points of failure, censorship, and manipulation.

How They Work: Conditions & Actions

Think of Smart Contracts as 'if-then' statements. They are programmed with specific conditions and corresponding actions.

  • Condition: If X happens...
  • Action: ...then automatically do Y.

These conditions can be anything from a specific date passing to a certain amount of cryptocurrency being received.

A Vending Machine Analogy

A simple way to understand Smart Contracts is to compare them to a vending machine:

  • Condition: You insert money and select a drink.
  • Action: The machine automatically dispenses your drink.

The vending machine guarantees the outcome without a human operator, just like a Smart Contract.

Why Smart Contracts Matter

Smart Contracts are revolutionary because they enable:

  • Trust: Automated, transparent agreements.
  • Efficiency: Eliminating intermediaries and delays.
  • Innovation: Powering DApps, DeFi, NFTs, and more.

They are the backbone of a new, programmable internet.

Quick Check: Smart Contract Traits

Which of the following are key characteristics of Smart Contracts?

Recap: Your Smart Contract Journey

You've learned that Smart Contracts are self-executing, immutable, transparent, and decentralized agreements written in code on a blockchain.

They power a new era of trustless and efficient digital interactions, forming the foundation of many Web3 applications. Next, we'll dive into the EVM and Gas!

Frequently asked questions

Is the “What are Smart Contracts?” lesson free?

Yes — the full text of “What are Smart Contracts?” is free to read here on the web, and the Web3 & DApp Development Fundamentals course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Web3 & DApp Development Fundamentals course, upgrade to CoddyKit PRO.

What will I learn in “What are Smart Contracts?”?

Learn the definition, purpose, and key characteristics of smart contracts as immutable, self-executing code on the blockchain. You practise Web3 & DApp Development Fundamentals with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Web3 & DApp Development Fundamentals?

No prior experience is required. Web3 & DApp Development Fundamentals on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 3, so you can start here or from the beginning and move at your own pace.

How long does the “What are Smart Contracts?” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Web3 & DApp Development Fundamentals lesson?

Yes. Every Web3 & DApp Development Fundamentals lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. The Ethereum Blockchain
  2. What are Smart Contracts?
  3. EVM & Gas Mechanics
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