Wallets, keys and seed phrases: key words
Read the word, say the meaning out loud, then open the card.
Wallet
An app or device that holds your keys and lets you see balances, send and receive crypto, and sign in to apps. The coins themselves stay on the blockchain. Source
Private key
A huge random number that signs transactions. Anyone who has it controls the account, so it must stay secret. Source
Public key
A key worked out from the private key by one-way maths. It lets others check your signatures, but it can't be used to approve transactions. Source
Address
The identifier you share so others can pay you. On Ethereum, it is the last 20 bytes of the Keccak-256 hash of the public key, written as 0x and 40 hex characters. Source
Externally-owned account (EOA)
An ordinary Ethereum account controlled by a private key. With the key you can do anything; without it, nothing. Source
Digital signature
Proof, made with a private key, that the key's owner approved exactly this data. Anyone can check it, and checking it doesn't reveal the key. Source
Checksum
Extra information added to an address or phrase so that software can spot most typing mistakes. Source
EIP-55
An Ethereum standard that hides a checksum in which letters of an address are capitals. Source
Recovery phrase (seed phrase)
A list of 12 to 24 words that can rebuild every key in a wallet. Anyone who has it can drain the wallet. Source
BIP-39
The standard that turns 128 to 256 random bits, plus a checksum, into words from a list of 2,048. Source
Entropy
The random bits a wallet starts from. A 12-word BIP-39 phrase carries 128 bits. Source
HD wallet
A hierarchical deterministic wallet: one seed grows a whole tree of keys, so one backup covers them all. Source
Derivation path
The address of one key in an HD wallet's tree, such as m/44'/60'/0'/0/0. It names the purpose, coin type, account, change chain and address index. Source
Watch-only wallet
A wallet that holds addresses or public keys but no private keys, so it can watch balances and payments but can't spend. Source
Typed data (EIP-712)
A standard way to sign structured messages, so a wallet can show what each field means before you sign. Source
Blind signing
Approving something your wallet can't show in readable form, such as a raw hash. Ledger compares it to signing a blank cheque. Source