A payment is a signed message
When someone “sends bitcoin,” they are not emailing a file. They broadcast a transaction: a message that says which previous outputs to spend, where the value should go, and a fee for the network. The message is signed with the private key that controls those outputs. Nodes check the signature and that the coins have not already been spent.
You can share an address to receive funds. You should not share the key that can spend them. That is the same rule as the wallets lesson.
Inputs, outputs, and change
Bitcoin does not keep a simple “account balance” the way a bank app does. Value sits in unspent outputs (UTXOs). A payment consumes one or more of those outputs and creates new ones — typically one to the recipient and one back to you as change, minus the fee.
You do not need to compute this by hand. Wallet software does it. The idea worth keeping: you are reassigning specific pieces of value, not decrementing a private database row.
- Amount — what the recipient should be able to spend later.
- Fee — the leftover that miners may collect. Higher fees often confirm faster when the network is busy.
- Change — what returns to an address you control.
Mempool, blocks, and confirmations
After broadcast, a transaction usually waits in the mempool (a queue of not-yet-included payments). Miners choose transactions to include in the next block — often preferring higher fees. When a block that contains your payment is added, you have one confirmation. Each block after that is another.
People wait for more confirmations when the amount is large because a block can be orphaned in a short chain reorganization. There is no universal “safe” number that this classroom can bless. Exchanges publish their own deposit policies. Those policies are theirs, not ours.
Unconfirmed does not mean “invisible.” It means not yet in a block. It also does not mean reversible by you. Replacement is a special case (some wallets signal that a fee can be bumped). It is not a customer support refund.
Why you cannot reverse it like a card
Card networks are built around merchants, chargebacks, and an issuer in the middle. Bitcoin’s design assumes that a valid, confirmed spend is final for the protocol. If you send to the wrong address, the network will not claw it back. If you are scammed, the ledger still shows a valid payment.
That is one reason to practice first, and one reason the scams lesson exists. Slowing down is not a lack of conviction. It is how you avoid a permanent mistake.
What a BitBuddy “buy” is not
The dashboard quick trade updates a practice balance. It does not create an on-chain transaction, does not enter a mempool, and does not pay a miner. The number you see is a classroom fill at a cached or simulated price.
If you later use a real wallet or exchange, read that product’s fee schedule and deposit rules. BitBuddy will not place that order for you.
Build a toy transaction
Pick classroom UTXOs, choose a fee rate, and watch inputs − send − fee = change before a fake TXID hits the mempool. DEMO ONLY — not Bitcoin.
Next on the path
Transactions land in blocks. The next lesson is what a blockchain is, including a live height/hash snapshot and a six-block teaching chain.