Wallet

Definition: Software or hardware that holds the private keys controlling access to blockchain assets, the “account” a person uses to send and receive cryptocurrency or interact with smart contracts.

How It Works

A wallet generates a public/private key pair, similar in spirit to asymmetric encryption
The private key is a large random number, the public key is mathematically derived from it, and the address (what you actually share) is usually a shortened hash of the public key
The public key or address is shareable, like a bank account number, anyone can send funds to it
The private key must never be shared, whoever holds it has full, irreversible control of the funds, with no password reset or customer support to recover it
Most wallets generate a human-readable seed phrase (typically 12 or 24 words) that can regenerate every key pair the wallet controls, this phrase is the actual master secret, the private key itself is just derived from it
Sending a transaction means signing it with the private key, producing a signature anyone can verify against the public key without ever seeing the private key itself
Signing happens locally, the private key never needs to leave the wallet, only the signed transaction and the public key are broadcast to the network
A wallet doesn’t actually “store” coins the way a physical wallet stores cash, the assets live on the blockchain ledger, the wallet just stores the keys that prove and grant control over them
The same wallet can typically hold multiple accounts (addresses) and interact with multiple different blockchains, provided the wallet software supports each chain’s address format

Wallet Types

Type	Custody	Convenience	Typical use
Hot wallet (software/browser extension)	Non-custodial, keys on an internet-connected device	High	Everyday transactions, DeFi/NFT interaction
Hardware wallet	Non-custodial, keys on an offline device	Medium	Long-term holding, larger balances
Custodial wallet (exchange account)	Custodial, exchange holds the keys	Highest	Trading, beginners, no key management
Multisignature wallet	Non-custodial, requires multiple keys to approve	Low	DAO treasuries, shared or high-value funds
Paper wallet	Non-custodial, keys printed/written offline	Very low	Cold, long-term storage, rarely used today
Smart contract wallet	Non-custodial, logic-based (social recovery, spending limits)	Medium	Users wanting programmable security features

Key Derivation (HD Wallets)

Modern wallets are “hierarchical deterministic” (HD), a single seed phrase can derive an entire tree of key pairs instead of needing a separate backup per address
BIP-32 defines the mathematical scheme for deriving child keys from a parent key deterministically
BIP-44 defines a standard derivation path structure, e.g. m/44'/60'/0'/0/0, so different wallets can reconstruct the same accounts from the same seed phrase
The path’s coin-type segment (e.g. 60' for Ethereum) is why the same seed phrase produces different-looking addresses on different chains, despite deriving from the same root
This is why importing one seed phrase into a different wallet app usually restores the same set of addresses, they’re following the same standard derivation path
Losing the seed phrase means losing every derived key at once, which is exactly why it, not any individual private key, is the thing that must be backed up

Under the Hood

Worked example: seed phrase entropy

Given: a standard 12-word BIP-39 seed phrase is chosen from a list of 2,048 possible words, with built-in checksum bits reducing the truly random portion to 128 bits of entropy
Step: the number of possible seed phrases is roughly 2^128, an astronomically large number, far more than the roughly 2^80 combinations security researchers consider computationally infeasible to brute-force
Answer: guessing someone’s specific seed phrase by random trial is not a realistic attack, real-world thefts almost always come from the phrase being stolen, phished, or carelessly stored, not cracked

Worked example: verifying a signed transaction

Given: a wallet signs a transaction “send 1 ETH to address 0xAbc…” using its private key, producing a signature
Step: the network takes the signature, the transaction data, and the claimed sender’s public key, and runs a verification function
Step: the math confirms the signature could only have been produced by the private key matching that public key, without the network ever seeing the private key
Answer: the transaction is accepted as authentically authorized by the key holder, this asymmetric signing/verifying process is what replaces a bank’s identity check with pure mathematics

Worked example: multisig threshold

Given: a DAO treasury multisig wallet is configured as “3-of-5,” any 3 of 5 designated signers must approve a transaction for it to execute
Step: a proposal to move 100,000 USDC is created and 2 signers approve it
Step: the transaction cannot execute yet, it’s below the 3-signature threshold, a 3rd signer must approve
Answer: once the 3rd signature is collected, the transaction executes, no single signer, or even any 2 colluding signers, can move funds alone

Why It Matters

Unlike a bank account, there’s no central authority to reverse a mistake or recover lost access, losing a private key means losing the assets permanently
Gives the holder direct, self-sovereign control over their assets, no institution can freeze, seize, or block a non-custodial wallet’s funds without the private key
Is the single point of interaction for essentially everything else in this glossary, DeFi, NFTs, and DAO voting all happen through a wallet signing transactions
Makes “not your keys, not your coins” a load-bearing security principle rather than a slogan, funds on an exchange are only as safe as that exchange’s own security and solvency
Acts as a portable, chain-agnostic identity, the same wallet address can hold assets and interact with contracts across many different applications without a separate login for each
Lets multisig and smart contract wallets encode organizational policy (spending limits, required approvals) directly into how funds can move, instead of relying purely on internal process

Common Pitfalls

Storing a private key or seed phrase digitally in an unencrypted place, a screenshot, a plain text file, a note-taking app, a common and preventable cause of theft
Signing a malicious transaction without understanding what it actually authorizes, a common phishing vector in Web3, the wallet UI shows a request, not a guarantee that request is safe
Approving unlimited token spend for a contract to save a small amount of gas on future transactions, an unlimited approval to a later-compromised contract can drain far more than intended
Sending funds to an address copied from a “poisoned” transaction history, attackers send tiny amounts from a lookalike address hoping a user copies the wrong one later out of habit
Losing a seed phrase with no backup, or keeping only one copy in a location vulnerable to fire, flood, or theft
Confusing a wallet address with a wallet app, sending assets to the correct address on the wrong network (e.g. an Ethereum address on a chain that doesn’t support that asset) can permanently strand funds
Trusting a fake wallet app or browser extension downloaded from outside the official source, malicious clones exist specifically to capture seed phrases on entry
Typing a seed phrase into any website or “wallet recovery” support chat, no legitimate wallet provider or support agent will ever ask for it
Assuming a hardware wallet alone makes a transaction safe, the device only protects the private key, it still shows you exactly what you’re told to sign, blind-signing a malicious request is still possible

Comparison

	Non-custodial software wallet	Hardware wallet	Custodial (exchange) wallet	Multisig wallet
Who controls the keys	The user	The user, offline	The exchange	Multiple designated key holders
Recovery if device is lost	Yes, via seed phrase	Yes, via seed phrase	Yes, via exchange account recovery	Depends on signer setup
Vulnerable to exchange hack	No	No	Yes	No
Vulnerable to phishing/malware	Yes	Lower, keys stay offline	Account-level phishing risk	Requires compromising multiple signers
Typical user	Active DeFi/NFT user	Long-term holder	Beginner, trader	Organization, DAO treasury, shared funds
Setup complexity	Low	Medium	Lowest	High

Example

MetaMask is a widely used non-custodial browser-extension wallet for interacting with Ethereum and other EVM-compatible blockchains, it generates and stores private keys locally in the browser, encrypted by a user-chosen password, and never transmits the keys anywhere.

FAQ

Can I recover a wallet if I lose my device but still have my seed phrase? Yes, importing the same seed phrase into a new wallet installation regenerates the identical key pairs and access to the same funds.

Does a wallet need to be online to sign a transaction? No, hardware wallets specifically sign offline, only the signed result needs to go online to be broadcast.

Is a custodial exchange account technically a wallet? Loosely, yes, but the exchange holds the actual private keys, the user only has login credentials to an account, which is a meaningfully different trust model.

What’s the difference between a wallet address and a private key? The address is safe to share and receives funds, the private key must stay secret and is what actually authorizes spending, confusing the two is a common beginner mistake.

Can two different wallet apps share the same address? Yes, if they’re both derived from the same seed phrase using the same derivation standard, the underlying keys and address are identical regardless of which app is used to access them.

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