Seed phrase, private key, public key or address? A safe UK beginner map

A seed phrase is the human-readable backup for an HD wallet. It can be used to recreate the wallet’s key tree, so keep it secret. A private key authorises spending from one Bitcoin key. A public key is the matching public value used to derive or check receiving information. A Bitcoin address is the shareable destination for a payment. Share an address when someone needs to pay you; never share a seed phrase or private key.

That is the short version. The terms overlap because an HD (hierarchical deterministic) wallet can derive many key pairs and addresses from one starting point. This guide stays with Bitcoin and HD-wallet terminology, rather than repeating the broader crypto wallet, private key and seed phrase guide.

The four terms in one table

Term	What it is in a Bitcoin HD wallet	Keep it secret?	Can you share it?
Seed phrase (mnemonic)	A sequence of words representing wallet backup data. In BIP-39, the words are converted into a binary seed that can be used with BIP-32 or a similar scheme. [3]	Yes	No
Private key	A secret value for one key pair. Its corresponding public key can be derived from it, and it is needed to sign a transaction spending the relevant bitcoin. [2]	Yes	No
Public key	The public half of a key pair. In an HD wallet, public child keys can be derived from an extended public key for non-hardened paths. [2]	Usually not, but treat it as sensitive wallet information	Only when you understand the scope
Address	A payment destination derived from public wallet data. It is the practical detail you give someone who is sending bitcoin. [1][2]	No	Yes, for receiving

The red/green rule is simple:

Red: never share your seed phrase, private key, extended private key or any wallet backup that can restore spending authority.
Green: normally shareable is the Bitcoin address you want someone to pay. A public key can be shareable too, but it may reveal more about the wallet’s structure or activity than one address.

What a seed phrase does

People often call a mnemonic sentence a “seed phrase”. In the BIP-39 specification, it is a group of words generated from entropy and a checksum. The standard describes 12, 15, 18, 21 or 24-word sentences, depending on the original entropy size. [3]

BIP-39 then converts the mnemonic and an optional passphrase into a 512-bit binary seed. That seed can feed BIP-32, which builds a hierarchy of related keys. [3][2]

The important practical point is that the phrase is not a list of coins and it is not an address. It is backup material from which wallet software can recreate the keys and addresses. If somebody obtains the complete phrase, they may be able to recreate the wallet elsewhere and spend its funds. Bitcoin’s developer documentation makes the same warning about a leaked seed in deterministic wallets. [1]

A passphrase, where the wallet design supports one, is not a replacement for protecting the mnemonic. BIP-39 treats the passphrase as an additional input to seed derivation; a different passphrase produces a different seed. [3] Losing it can make the expected wallet appear empty, while exposing the phrase still exposes the part of the backup you thought was protected. Do not treat a passphrase as a reason to show the words to anyone.

What a private key does

A private key is the secret value behind one Bitcoin key pair. The matching public key is calculated from it using the elliptic-curve system used by Bitcoin. [2]

The private key gives the ability to sign a transaction for outputs controlled by that key. It is not the same thing as a seed phrase: a seed phrase can back up a whole HD wallet, while a private key normally relates to one branch or one key. Importing or exporting a private key can also sit outside the wallet’s normal HD backup structure, so it should not be used as a casual substitute for the wallet’s documented backup.

An extended private key is more powerful than a single private key. BIP-32 describes extended private keys as a private key combined with a chain code, and says that knowing one allows reconstruction of descendant private and public keys. [2] Treat an extended private key as wallet-level secret material, not as something safe to paste into a message or website.

What a public key does

A public key is derived from the private key and can be used to derive a corresponding receiving route. With HD wallets, an extended public key can provide visibility into a branch of public child keys without giving the holder the private keys needed to sign. BIP-32 calls this the “neutered” version of an extended private key and limits public-child derivation to non-hardened children. [2]

That does not make every public key harmless in every situation. A single public key can be linked to activity, and an extended public key can expose a larger set of addresses and balances to whoever receives it. Share the smallest public item that solves the job: normally one receiving address, not a wallet-wide extended public key.

What a Bitcoin address is

An address is the payment destination you can give to another person. It is derived from public wallet information, but it is not the same as the public key itself. BIP-32 notes that traditional Bitcoin addresses use a hash of the serialized public key, while the exact address format depends on the wallet and output type. [2]

An address does not let somebody spend your bitcoin. It can, however, let them see payments and balances associated with that address on the public blockchain. Reusing addresses can make activity easier to link, so many HD wallets create fresh receiving addresses. The Bitcoin developer documentation describes HD wallets as deriving multiple key chains from one root, including an external chain for public addresses and an internal chain for other wallet operations such as change. [1][2]

Use the address your wallet shows for the payment you are expecting. Do not alter characters by hand, and check the network and amount before a transaction is sent. This article does not recommend a particular wallet or tell you how to use a provider.

How the pieces fit together

A simplified HD-wallet chain looks like this:

text seed phrase + optional BIP-39 passphrase ↓ binary seed ↓ BIP-32 master key ↓ child private/public key pairs ↓ public key information and addresses

The arrows describe derivation, not a list of things you should share. The secret starts at the top and remains secret as it feeds the private-key side of the tree. Public information can be derived for receiving and monitoring, but it does not flow backwards into a private key: BIP-32 explicitly says that a public parent key cannot produce a private child key. [2]

A wallet may also show technical labels such as xpub and xprv. These are serialised extended public and private keys in BIP-32’s format. The xpub label does not mean “safe to publish everywhere”; it can reveal a branch of wallet activity. The xprv label is a clear warning that the value contains private wallet authority. [2]

A quick decision test before you send anything

Ask what the other person needs:

They are paying you: send the requested Bitcoin address, preferably copied from the wallet’s receiving screen and checked before sending.
They are helping identify a transaction: an address or transaction ID may be enough. A seed phrase is not.
They are asking for a backup, recovery phrase or private key: stop. Do not send it in chat, email, a form or a screenshot.
They request an extended public key: understand that it can reveal more than one address. Share it only for a specific, trusted purpose and only if you accept that visibility.

Anyone who asks for a seed phrase to “verify”, “unlock”, “sync” or “recover” funds is asking for the wallet’s most important secret. A genuine payment does not require it. For more scam warning signs, see common crypto scams, phishing and fake support.

The plain-English takeaway

Seed phrase: whole-wallet recovery words. Secret.
Private key: spending authority for one key. Secret.
Public key: public cryptographic counterpart; an extended version can expose a branch. Share carefully.
Address: payment destination. Normally shareable for receiving.

If you remember one line, make it this: share an address to receive Bitcoin; never share the words or keys that can spend it.

Internal links

Sources

[1] https://developer.bitcoin.org/reference/wallets.html — Bitcoin Developer Guide: Wallets
[2] https://github.com/bitcoin/bips/blob/master/bip-0032.mediawiki — BIP-32: Hierarchical Deterministic Wallets
[3] https://github.com/bitcoin/bips/blob/master/bip-0039.mediawiki — BIP-39: Mnemonic code for generating deterministic keys