🌱 Module 3: Your First Transaction

🤔 Before We Begin: What Happens When You Click "Send"?

Think about this:

When you send an email, it passes through your email provider's servers. They could read it, block it, or redirect it. The recipient trusts that Gmail or Outlook delivered your message unchanged.

But what about Bitcoin?

  • Who processes the transaction when there's no Bitcoin company?
  • How do you know it won't be reversed or modified?
  • What prevents someone from copying your Bitcoin and spending it twice?
  • Why do some transactions take seconds while others take hours?

Let's answer these questions by actually making a transaction.

Part 1: Receiving Bitcoin

Before you can send bitcoin, you need to receive some. Let's start here because it's simpler and helps you understand Bitcoin addresses.

What is a Bitcoin Address?

A Bitcoin address is like an email address or bank account number. Anyone can send bitcoin to it, but only you (with your private keys) can spend from it.

📍 Address Types

There are three main address formats (they all work the same, just different technical standards):

  • Legacy (P2PKH): Starts with "1" - 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa
  • SegWit (P2SH): Starts with "3" - 3J98t1WpEZ73CNmYviecrnyiWrnqRhWNLy
  • Native SegWit (Bech32): Starts with "bc1" - bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh

Recommendation: Use Native SegWit (bc1) - it has the lowest fees and best privacy.

How to Receive Bitcoin

1

Open Your Wallet

Launch your Bitcoin wallet app (e.g., BlueWallet, Muun, etc.)

2

Click "Receive"

This generates a new receiving address for you

3

Copy Address or Show QR Code

In person: Show QR code for scanning
Online: Copy address and send via text/email

4

Wait for Confirmation

You'll see the transaction appear in your wallet, usually within seconds

⚠️ Important: Address Reuse

For privacy, generate a new address for each transaction. Most modern wallets do this automatically. Old addresses still work, but using a fresh address for each payment makes it harder for others to track your total balance.

Part 2: Sending Bitcoin

Now comes the exciting part—sending Bitcoin. This is where you'll see the magic of peer-to-peer money in action.

Before You Send: The Checklist

Verify the Address

Bitcoin transactions are irreversible. There's no "undo" button. Always double-check the recipient's address—copy/paste carefully or scan QR code.

Check Your Balance

Make sure you have enough Bitcoin to cover both the amount you're sending AND the network fee.

Choose Fee Priority

Higher fee = faster confirmation. Low priority = cheaper but slower. We'll explain this in detail below.

Start Small

For your first transaction, send a tiny amount to test. Once you're comfortable, send the rest.

Sending Process

  1. Open your wallet and click "Send"
  2. Enter recipient's address (paste or scan QR code)
  3. Enter amount (in BTC or your local currency)
  4. Choose fee (Low/Medium/High priority)
  5. Review transaction - triple check everything!
  6. Confirm - enter PIN/password if required
  7. Transaction broadcast - sent to Bitcoin network!

What just happened? Your wallet created a transaction, signed it with your private key, and broadcast it to thousands of Bitcoin nodes worldwide. Within seconds, miners around the world saw your transaction and started competing to include it in the next block.

Understanding Transaction Fees

Bitcoin transactions include a small fee paid to miners. This isn't a company fee—it's a market-driven reward for miners securing the network.

How Fees Work

Miners prioritize transactions with higher fees because they want to maximize revenue. Think of it like a bid in an auction:

  • High fee (10+ sats/vB): Next block (~10 minutes)
  • Medium fee (5-10 sats/vB): Within 1-3 blocks (~30 minutes)
  • Low fee (1-5 sats/vB): Could take hours or days

What's a "satoshi per virtual byte" (sat/vB)?

Bitcoin fees are measured in satoshis per virtual byte of transaction data. One Bitcoin = 100,000,000 satoshis (sats).

Example: A typical transaction is ~140 vB. At 5 sat/vB, the fee would be 700 sats (about $0.70 at $100,000/BTC).

When to Use Different Fee Levels

  • High Priority: Urgent payments, time-sensitive transactions
  • Medium Priority: Normal day-to-day payments
  • Low Priority: Moving funds to cold storage, no rush

Pro Tip: Check mempool.space to see current network fees before sending.

Interactive: Mempool & Fee Market

Visualize how Bitcoin's mempool works! See how miners select transactions, practice fee estimation for different scenarios, and understand confirmation timing. Master the fee market through interactive simulations!

Launch Mempool Visualizer →

Complete all 5 steps to understand fee markets and practice realistic fee estimation scenarios!

Transaction Confirmations

After broadcasting your transaction, you'll see it as "pending" or "unconfirmed" in your wallet. This means miners have seen it but haven't included it in a block yet.

The Confirmation Process

  1. 0 confirmations (Unconfirmed): Transaction broadcast, in mempool, waiting for miner
  2. 1 confirmation: Included in a block, generally considered "received"
  3. 3 confirmations: Very safe for most transactions (~30 minutes)
  4. 6 confirmations: Standard for exchanges, essentially irreversible (~1 hour)

Why wait for confirmations? Each confirmation makes it exponentially harder to reverse the transaction. After 6 confirmations, reversing would require more computing power than exists on Earth.

Real-World Analogy

Think of confirmations like wet concrete:

  • 0 confirmations: Concrete is still liquid (transaction can technically be replaced)
  • 1 confirmation: Concrete is setting (hard to change, but possible with effort)
  • 6 confirmations: Concrete is rock solid (practically impossible to reverse)

Interactive Transaction Builder

Practice building Bitcoin transactions in a safe environment. Experiment with fees, addresses, and amounts to understand how transactions work.

Launch Transaction Builder →

This is a simulation—no real Bitcoin is used. Practice as much as you want!

💭 What Did You Learn?

Now that you've built a transaction, let's revisit those questions from the beginning:

  • Who processes Bitcoin transactions? Thousands of independent miners worldwide competing to include your transaction.
  • How do you know it won't be reversed? Cryptographic proof + exponential confirmation security = mathematical certainty.
  • What prevents double-spending? The UTXO model ensures each coin can only be spent once—miners reject duplicates.
  • Why do speeds vary? It's a fee market—higher fees = higher priority in the queue.

The Profound Realization: You just moved money across the internet without asking anyone's permission. No bank. No payment processor. No middleman. Just math, cryptography, and a global network of independent computers.

Common Mistakes to Avoid

🚫 Don't Do This

  • Sending to wrong address: Always verify! Bitcoin transactions are irreversible.
  • Forgetting about fees: Make sure you have enough for amount + fee.
  • Using extremely low fees during high demand: Your transaction could be stuck for days.
  • Panicking during delays: If fee is reasonable, transaction will confirm eventually.
  • Screenshot private keys/seeds: Never share or photograph sensitive information.
  • Sending to exchange before checking memo: Some exchanges require a memo/tag.

🧪 Interactive: Testnet Practice Guide

Practice with real Bitcoin transactions—without risking real money! Get testnet coins from faucets and send your first risk-free transaction.

Launch Testnet Practice Guide →

Follow the 5-step guide: Get wallet → Get address → Get testnet coins → Watch confirmations → Send!

Key Takeaways

  • Bitcoin addresses are like email addresses—anyone can send to them
  • Always double-check recipient address before sending
  • Transactions are irreversible—there's no "undo" button
  • Fees are paid to miners, not a company (it's a free market)
  • Higher fee = faster confirmation, lower fee = longer wait
  • 1 confirmation is usually enough, 6 is rock-solid secure
  • Use new addresses for each transaction (better privacy)
  • Start with small test transactions to build confidence
  • You just used peer-to-peer money without asking permission!

🎉 Congratulations!

You've completed the most important milestone in your Bitcoin journey: making your first transaction.

You now understand:

  • ✅ What Bitcoin is and why it matters
  • ✅ How to set up and secure a wallet
  • ✅ Where to acquire Bitcoin
  • ✅ How to send and receive bitcoin

Next up: Stage 4 - Staying Safe
Now that you have Bitcoin, let's make sure you can keep it secure for the long term. We'll cover security fundamentals, backup strategies, and how to protect yourself from the most common threats.