Bitcoin
The network, protocol and monetary unit. Valid issuance rules limit supply to approximately 21 million BTC.
Explain in the Atlas →Bitcoin mainnetBlock ···Epoch 04
START HERE · FROM BASICS TO SELF-CUSTODY
Your first bitcoin.
Step by step.
A practical guide to buying, wallets, Seed Phrase and UTXO. The goal is to understand what you buy, try a small transfer to self-custody and verify recovery without disclosing secrets.
10 chaptersSmall test transfer0 affiliate links
Educational content, not individual investment, tax or legal advice.00 / BASICS
Six terms before your first transaction
Distinguish the network, service, wallet and backup. Similar names do not necessarily mean the same control over funds.
Satoshi
A common accounting unit in Bitcoin transactions. 1 BTC = 100,000,000 sats; a fraction of bitcoin can be purchased.
Explain in the Atlas →Address
Information for receiving a payment. Verify the entire address through a trusted procedure; publishing it may link your identity to payments.
Explain in the Atlas →Private key
Secret data for creating a signature. Spending requires meeting all output conditions, such as further signatures in Multisig.
Explain in the Atlas →Seed Phrase
Recovery material for a compatible wallet’s keys. It is not a resettable password; a passphrase and other information may be required.
Explain in the Atlas →UTXO
An unspent transaction output. The wallet selects outputs for a new payment and returns any change to a change address.
Explain in the Atlas →THE BASIC DISTINCTIONAn exchange may facilitate a purchase. A wallet may manage keys or merely monitor addresses. A complete, verified backup enables recovery.
01 / CUSTODY
Three ways to hold funds, three risk models
Custodial Exchange
The operator controls keys and withdrawal terms. You bear its operational, legal and insolvency risks; do not judge protection by the app’s name alone.
- + account recovery under service rules
- − the custodian controls the keys
- − phishing and withdrawal restriction risks
Self-custodial mobile wallet
In a self-custodial mobile wallet, keys are on a network-connected device. A mobile app can also be custodial or a Watch-only Wallet; being on a phone does not imply you hold the keys.
- + quick everyday use
- + your own keys with self-custody
- − larger digital attack surface
Hardware Wallet
A signing device is designed to keep keys separate from an ordinary computer. Verify authenticity, firmware and information on its display; the device does not remove the risk of a faulty backup.
- + keys separated from the computer
- + recovery using a complete backup
- − responsibility for a safe process
02 / PRACTICAL ROUTE
From a small test to self-custody
Proceed step by step. A tick records only your progress, not verified safety; the state is stored locally if your browser allows it.
BEFORE SENDING MONEY
Clarify what you are buying
Bitcoin is a network and a digital asset. Buying through a service does not itself mean you control the keys; the actual product and withdrawal options matter.
- 1 BTC = 100,000,000 sats. You can buy a fraction of bitcoin; minimum purchases and withdrawals depend on the service.
- The price can fall sharply and stay low for a long time. Your test amount must be small enough that you can bear losing it entirely.
- For the first test, do not use credit, leverage, futures or funds needed for everyday expenses. A small amount does not remove the risk of mistakes.
IN PRACTICE
Write down the amount, reason for buying and your own limits. Any numerical example of a price decline is not a limit on possible losses.
THE ON-RAMP
Verify the operator and actual BTC withdrawals
For a purchase with ordinary currency, compare a service that offers the intended product and lets you withdraw bitcoin to your own wallet.
- In the EU, check the legal entity and scope of authorization in the current ESMA/MiCA register and with the relevant supervisor. Elsewhere, use the local regulator. Authorization does not guarantee returns or the safety of every product.
- Distinguish withdrawable bitcoin, a balance with a custodian and a financial product tracking the price. Legal claims depend on the contract and jurisdiction; a “buy” button does not establish control of your own keys.
- Compare the total price: trading fee, spread, deposit and withdrawal. “No fee” does not rule out an unfavorable exchange rate.
- Check login security, protection for new withdrawal addresses, time delays, pricing and support. Available features differ between services.
IN PRACTICE
Provider links are for your own verification, not a ranking. Check the current conditions for your country directly before signing up.
ACCOUNT SECURITY
Secure the account before the first deposit
Compromised email, login credentials or fake support can put funds at risk without breaking the Bitcoin protocol.
- Use a long, unique password and secure your email too. A password manager helps with login credentials; this does not mean a Seed Phrase belongs in it.
- Where available, use phishing-resistant authentication such as a passkey or security key. TOTP adds protection, but a fake website can capture a code you type; SMS has additional risks.
- Store account recovery codes securely. If an allowlist of withdrawal addresses or a time lock is available, configure it and understand how to recover access.
- Verify the domain independently, then use a saved bookmark. An advertisement, message or unsolicited support link is not proof of authenticity.
IN PRACTICE
Send KYC data only to a verified service. Do not give an unsolicited contact your Seed Phrase, PIN or one-time codes, and do not allow remote control.
FIRST TRADE
Try a small spot purchase
The first attempt should test the process from payment to withdrawal. Choose a supported payment method and an amount you can afford to lose.
- Compare the costs and terms of bank transfers and cards. Check the service’s requirements for matching payer names, limits and crediting times.
- Verify that you are buying spot BTC in the selected currency, not a CFD, futures, a leveraged product or yield-bearing lending.
- A market order normally fills at available prices and can suffer slippage. A limit order restricts the price but does not guarantee execution, and it can fill immediately if the limit is already met.
- Save the date, BTC amount, price, fees, currency rate and trade confirmation. You will need records for your own checks and applicable obligations.
IN PRACTICE
A larger purchase is not needed to test functionality. Consider another transfer only after a small trial of self-custody and a usable backup.
WHO HOLDS THE KEYS
Distinguish accounts, address monitoring and your own keys
Bitcoin does not sit inside a device. A wallet works with keys or output information; not every application can sign independently.
- With a Custodial Exchange, the operator controls the keys, and withdrawals depend on its operations and terms. Assess the exact legal position under the contract and local law.
- A self-custodial mobile wallet can hold keys on a connected device. Another mobile app may be custodial or a Watch-only Wallet; check the actual model.
- A Hardware Wallet is a signing device designed to separate keys from the computer. Its origin, firmware, display and signing procedure are part of the security model.
- Suitable custody depends on threats and your ability to back up and recover safely. A more complex device does not replace a process you understand.
IN PRACTICE
Before changing custody, establish who holds the keys, how a signature is created and how recovery works. A Watch-only Wallet without the relevant keys cannot spend funds by itself.
SIGNING DEVICE
Verify the device and create your own backup
If you choose a Hardware Wallet, check the seller, device provenance and instructions for the exact model. A brand or intact packaging is not complete verification.
- Use the official application and the manufacturer’s authenticity and firmware checks. Check security advisories before generating a new backup.
- Initialize a new wallet yourself. Preprinted words, a preset PIN or an offer of an activated wallet are reasons to stop.
- Set a PIN according to the instructions. It restricts use of the device but does not replace a Seed Phrase or repair a disclosed backup.
- When receiving, compare the entire address on the trusted display. When signing, check the destination address, amount and fee shown by the device.
IN PRACTICE
The following links lead to manufacturer documentation. Before buying, compare supported features, backups, updates and security models; this is not a ranked recommendation list.
Trezor SafeDevice documentation and on-device backup verification.BitBox02 BTCDocumentation for the Bitcoin version and handling a microSD backup.Blockstream JadeDocumentation for supported models and signing methods.ColdcardDevice, PSBT and manufacturer security advisory documentation.LedgerDevice, application and security-model documentation.
THE CRITICAL BACKUP
Protect all the recovery information
A Seed Phrase may allow keys to be derived again without the original device or PIN. The same wallet may still require a passphrase and other information; Multisig requires the specified number of signatures.
- Keep recovery words complete, exact and in the correct order. Do not invent or translate them; avoid photographs, email, ordinary cloud storage and note-taking applications.
- Protect the backup from loss, fire, water, discovery and coercion. Choose copy counts and locations according to your threats; each additional copy also creates another opportunity for disclosure.
- No support service needs your recovery words. Recover through a verified procedure on a trusted device; with a Hardware Wallet, enter them on the device if that model supports it.
- Before entrusting more funds to a wallet, check its backup using a built-in check or safe recovery on a compatible device. Do not erase your only working wallet just to test.
IN PRACTICE
With BIP39, even a mistyped passphrase creates a valid different wallet. Back up the exact passphrase separately. Also retain the format, derivation paths and any Output Descriptor; correct words alone do not guarantee finding all funds.
FIRST WITHDRAWAL
Verify the whole address and a small transfer
Create a receiving address in a trusted wallet and compare it in full with the withdrawal destination. Checking only the beginning and end is not enough.
- For an ordinary Bitcoin on-chain address, select the corresponding Bitcoin network. Lightning Network, Liquid and other networks or tokens are not interchangeable without a specific supported conversion.
- The bc1 prefix is not proof of the correct recipient. Verify every character through a trusted procedure; do not take an address only from transaction history or an unsolicited message.
- After a small test, verify receipt in the wallet. An explorer display is not the same as your own verification; the required confirmation count depends on the amount and risk, and does not provide absolute finality.
- Before every further transfer, check the address, network, amount and fee again. A previous successful test does not guarantee the next form is correct.
IN PRACTICE
A small test limits the scale of a possible mistake, not every threat. If details disagree or you are under pressure, do not confirm the transfer.
UTXOS AND FEES
Consider UTXOs, fees and custodian risk
An incoming on-chain payment may create a new UTXO. Its future spending fee depends mainly on transaction virtual size and fee rate, rather than just the amount sent.
- Many small withdrawals may create many inputs for a future payment and increase its fee. The effect depends on the UTXOs actually selected and the transaction type.
- Accumulating a balance with a custodian to reduce withdrawal costs adds counterparty risk. Assess both effects together, instead of assuming one optimal amount for everyone.
- A wallet normally returns unspent change to its own change address. This output is not itself a second fee, but check that it belongs to your wallet.
- Lightning Network can make small payments easier, but it has its own liquidity, custody and backup requirements. Its recovery procedure is not interchangeable with an on-chain wallet’s.
- UTXO consolidation can reduce the future input count, but costs a fee now and links outputs for observers. Understand the privacy effect first.
IN PRACTICE
A sat/vB fee-rate estimate changes with demand and does not guarantee confirmation time. Check the total fee before signing, not just the suggested rate.
YEARS OF OPERATION
Plan maintenance, privacy and recovery
Self-custody must account for a lost device, moving home and being unable to act. A backup and an understandable plan are part of routine operation.
- Regularly check backup readability and availability. Verify updates according to the manufacturer, and have a usable recovery plan before making changes; do not act under pressure.
- A KYC service can link identity to withdrawals. Avoid unnecessary disclosure of balances and address reuse. An Extended Public Key (xpub) reveals addresses and history derived from its branch, not necessarily every wallet or account.
- Keep records of purchases, sales, transfers and fees. A transfer between your own addresses is not itself a trade with another person; still check tax and recordkeeping implications for your jurisdiction.
- An inheritance plan should let authorized people reach complete recovery without an easily accessible document exposing every secret. The legal and technical parts need to work together.
- Multisig and split backups address different threats and can also complicate recovery. They do not automatically remove all single points of failure; practice and the necessary supplementary data are required.
IN PRACTICE
Check that an authorized person can use the plan without your memory, while it still resists easy theft. Review security over time; ticking a chapter is not a certification.
03 / RECOVERY
Accounts, devices and backups protect different things
PIN
Restricts device use according to its security model.
It does not recover the wallet or protect a disclosed Seed Phrase.Seed Phrase
Helps derive keys again. Full recovery may require a passphrase, format, derivation paths or Multisig information.
Disclosure may enable theft; Multisig still requires the necessary number of signatures.Passphrase
With BIP39, it changes the wallet derived from the same words.
Even a typo creates a valid different wallet. Back up the exact passphrase separately; it cannot be reset.2FA
Adds protection to an account at a service. A passkey or security key resists phishing better than a TOTP code that you type.
It does not protect the keys or backup of a wallet you manage yourself.PHYSICAL BACKUP OPTIONS
complete words written by hand
durable material chosen for the threats
separate locations with controlled access
verified recovery under manufacturer instructions
DO NOT DISCLOSE SECRETS
through a photograph or screenshot
through email, ordinary cloud storage or notes
by sending them to supposed support
by entering them on an unverified website
04 / STOP
Warning signs: stop the process
01The device arrived with a preprinted Seed Phrase or a preset PIN.
02Supposed support contacted you first and wants recovery words, a 2FA code or remote access.
03Someone promises guaranteed returns, doubled BTC or a risk-free product.
04A website requests a Seed Phrase for synchronization, an upgrade or unlocking.
05An app offers a different network just because it is cheaper, without checking compatibility.
06The entire address does not match the one verified on a trusted device.
07You are under pressure or an unsolicited caller is dictating the steps.
08You are planning a large transfer without address verification, a small test and a usable backup.
05 / CHECKLIST
Steps for a first controlled purchase
Read the related chapter first and check that you understand the risk. A completed checklist is not a guarantee of the outcome.
- 01
Choose a small test amount whose total loss you can bear.
- 02
Verify the legal entity and current authorization for your country; confirm actual BTC withdrawals are available.
- 03
Create the account on a verified domain; use a unique password and secured email.
- 04
Where available, enable phishing-resistant authentication; store recovery codes securely and set withdrawal protection.
- 05
Check the price including the spread and all fees; try a small unleveraged spot purchase.
- 06
Choose a self-custody process you can manage and verify the device and application provenance.
- 07
Set up the new wallet yourself; use a newly generated backup and never words supplied by a seller.
- 08
Store the complete backup offline and verify it without erasing the only working wallet.
- 09
Create a receiving address and compare it in full through a trusted procedure.
- 10
Send a small test through the correct Bitcoin network; verify receipt and appropriate confirmations.
- 11
For any further transfer, check the address, network and fee again; keep records.
- 12
Prepare a recovery and inheritance plan without a single easily accessible document exposing every secret.
THE GOAL IS A VERIFIED PROCESSYou understand key control, have verified a transfer and can recover the wallet safely. This still does not remove price or operational risks.
QUESTIONS PEOPLE ACTUALLY ASK
Bitcoin guides: from questions to verification.
Choose a question about Bitcoin, issuance, buying, wallets or Lightning Network. Each guide connects explanations, practical limitations, primary sources and related Atlas entries.
01
Who controls Bitcoin?
No single party does. Developers publish software, miners propose blocks, businesses choose services and users decide which rules their nodes accept.
Read the guide →02Is Bitcoin stored in a wallet?
No. The network records spendable outputs; the wallet manages the keys and data needed to control them.
Read the guide →03Must I buy a whole bitcoin?
No. One bitcoin divides into 100 million satoshis, so you can buy a small fraction.
Read the guide →04Is buying by card always faster?
Crediting can be quick, but the purchase may cost more or face a waiting period. Compare the final amount and withdrawal availability, not just deposit speed.
Read the guide →05What happens if I lose my phone?
With a correct self-custody wallet backup, funds can usually be recovered elsewhere. Without a backup, keys may be permanently lost.
Read the guide →06Can I share a bitcoin address?
Yes, for receiving, but reusing it can reveal transaction links. Never share private keys or recovery words.
Read the guide →07What if the Hardware Wallet breaks?
Coins are not stored inside the device. A compatible recovery process can reconstruct the keys from the backup, provided you retained every required secret and configuration detail.
Read the guide →08Is a photo of the Seed Phrase acceptable if encrypted?
It creates copies, metadata and exposure to networked devices. Offline physical backups are generally easier to reason about and audit.
Read the guide →09Can support ask for my Seed Phrase?
No legitimate support procedure needs your recovery words. Treat a request to send them or enter them in a web form as an attempt to obtain the secret.
Read the guide →10Can I photograph my Seed Phrase?
A photograph creates a digital copy exposed to the device, its backups and cloud storage. A safer starting point is a complete readable offline backup with carefully planned access.
Read the guide →11Do lost coins reduce the limit?
They do not change the issuance ceiling, but they can reduce the amount that is actually spendable. The protocol cannot reliably distinguish a lost key from a very patient holder.
Read the guide →12Can a miner create extra bitcoin?
A miner can publish such a block, but nodes following the rules reject it. Hashrate cannot make an invalid coinbase reward valid.
Read the guide →13Does mining solve useful scientific problems?
Its direct product is an easily verifiable proof tied to a specific block header. Freely reusing the work for another task could weaken that commitment or introduce shortcuts.
Read the guide →14Does more Hashrate create more bitcoin?
Only temporarily between difficulty adjustments can blocks arrive faster. Retargeting brings the long-run issuance pace back toward the schedule.
Read the guide →15Are Lightning payments recorded on Bitcoin?
Channel opening and eventual settlement are on-chain. Individual intermediate balance updates normally remain off-chain unless a dispute or close requires publication.
Read the guide →16Are payments final instantly?
A successful recipient can usually treat the fulfilled conditional payment as final within the channel system, while ultimate dispute enforcement remains anchored to Bitcoin and its confirmation process.
Read the guide →17What does DCA stand for?
Dollar-cost averaging: regularly investing the same amount of money.
Read the guide →18Does DCA guarantee profit?
No. The result still depends on bitcoin’s future price, costs and holding period.
Read the guide →19Is Bitcoin a cryptocurrency?
Yes, it is commonly classified that way. But the broad category does not explain Bitcoin’s specific rules or mean other systems share its properties.
Read the guide →20Are all altcoins the same?
No. They differ in design, permissions, issuance, dependencies and risks. This comparison is neither an investment ranking nor a guarantee of returns from any of them.
Read the guide →06 / SOURCES
Verify against primary sources
Protocol, regulator and manufacturer documentation explains rules and specific procedures. A manufacturer link is not a rating or guarantee of its product; links are not affiliate links.
01
Bitcoin.orgHow transactions, keys and mining work
↗02Bitcoin.orgSecuring a Bitcoin wallet
↗03Bitcoin.orgChoosing a wallet type
↗04ESMAEuropean MiCA provider register
↗05Trezor LearnWhat 12, 20 or 24 backup words restore
↗06Trezor LearnPhishing and fake support
↗07mempool.spaceCurrent Bitcoin fee market
↗08Bitcoin BIPsTechnical wallet and seed standards
↗09TrezorOn-device backup check
↗10TrezorVerifying the whole receiving address
↗11NIST SP 800-63BPhishing-resistant authentication
↗12CoinkiteSecurity advisory on backup generation
↗13BIP 32Scope of extended-key derivation
↗14BIP 380Additional wallet recovery information
↗