Wallet

A friend sends bitcoin to an address from your wallet. They are not sending a coin file to your phone: they are creating a transaction on the Bitcoin network. Your wallet tracks whether the payment has arrived and been confirmed in a block, then reflects it in your balance. When you later want to pay someone, it prepares a new transaction. Authorizing that payment usually requires a digital signature, proof of the right to spend. The wallet creates it with a private key, secret information that it does not reveal to others when signing. The app and the network therefore have different roles: the wallet helps you make a payment, while the network checks its validity. [1]

A displayed balance often consists of several separate unspent amounts, known as UTXOs. The wallet finds them using the information it manages and checks which have already been spent. Simply monitoring them does not require private keys. A Watch-only Wallet can show incoming payments or prepare a payment proposal, but cannot sign it itself. This is useful, for example, for watching savings whose keys stay on a separate device. A screen showing an amount is therefore not proof that the app can send that money. [1]

With Self-custody, you control the keys needed to sign. You also take responsibility for protecting and recovering them. With a custodial service, the provider holds the keys and carries out withdrawals. The balance in its app shows how much its records allow you to withdraw; it does not mean you control the corresponding keys. Availability and the service’s rules also matter. Two apps can therefore display the same amount yet behave very differently if you lose access or the provider has problems. [1]

An address lets someone pay you. The wallet creates it from information defining how the received bitcoin can later be spent. You can send the address to the payer; knowing it alone does not normally let someone send your money elsewhere. A private key and a Seed Phrase have a different role. A Seed Phrase is a backup sequence of words from which supported wallets can recover keys. Do not send these secrets to anyone. Sharing an address still has privacy implications: someone who knows it can follow its public history. Using a fresh address for another payment helps avoid unnecessarily linking different payments. [1]

For a payment, the wallet selects suitable UTXOs, creates the recipient’s amount and any change, and proposes a fee. The transaction is then signed and passed to the network. The same device need not perform every step. PSBT is a format for passing an unfinished Bitcoin transaction between an app and a signer. A Hardware Wallet, a separate device that protects keys and creates signatures internally, can thus sign a proposal from a computer without giving the computer its keys. Check the destination address and amount on the device’s trusted screen. The device cannot know whom you actually intended to pay. [2]

Many modern wallets derive multiple keys from a common starting point, the seed, using BIP 32 rules. A Seed Phrase, used for example by BIP 39, helps recover that starting point; it is not merely a written version of one key. If you use a BIP39 passphrase, an optional extra input to derivation, you need it for recovery too. A typing mistake can open a different wallet without warning. Derivation-path information describes how individual keys are generated; the script type describes how spending conditions are written. These details may also be needed to tell recovery software how to find the right keys and addresses. With Multisig, where spending requires several signatures, also back up the signing rules and the cosigners’ public information. One wallet’s words alone may not be enough. [3] [4] [2]

An established mobile wallet can help you learn with small transactions and handle everyday payments. A larger long-term amount calls for more considered protection: where the keys are, who can reach them, and whether the backup will work. A separate signing device can reduce some risks from a compromised phone or computer, but cannot prevent mistakes when approving payments. Keeping spending money separate from savings can limit the impact of one mistake. The aim is not simply the most complicated setup; a procedure you do not understand or cannot use to recover access carries risks of its own. [1]

Your chosen app or device must support your wallet type and backup format. Having a written backup is not the same as knowing you can recover the wallet. The words must be complete, legible and in the right order, and any other required information must remain available. Use the safe backup-check or recovery procedure recommended for your wallet or device. Do not test it by entering real words into a page someone sent you to “verify your wallet.” Supposed support staff do not need them either. A lost phone can be replaceable if the correct backup restores the keys. Merely installing the same app or changing its password cannot restore missing original keys. [4] [5]

To show a balance, a wallet needs to learn the state of the relevant transactions. It may use the provider’s server or connect to your Full Node, a computer that independently checks Bitcoin’s rules. A server may learn relationships between addresses and queries, and need not show the same unconfirmed transactions as another node. Running your own node helps only if the wallet really uses it. That is separate from holding the keys: an app can leave signing entirely to you while still relying on someone else’s server for information. Self-custody and independent verification should therefore be assessed separately. [1]

Even the best device cannot help if you install a fake app, reveal recovery words or approve a payment to the wrong address. Phishing is a scam in which an attacker imitates a trusted website, message or support service to obtain secrets or persuade you to approve a harmful action. Verify where apps and updates come from, check payment details, and protect backups against loss or destruction as well. If someone else obtains the keys, a new app password does not invalidate their copy. Think of the wallet as your whole way of managing funds: the app, any signing device, the backup and your habits when using them. [2] [5]