What is Public key?

A public key is the half of a cryptographic key pair that can be shared. It is derived from the private key by a one-way function, so publishing it reveals nothing about the private key, and it lets anyone verify that a signature was produced by the matching private key. On most chains the wallet address is a shortened form of the public key, a hash of it on Bitcoin and Ethereum, which is why an address can be handed out without risk. In practice you will meet it as an address more often than as a key itself: wallets show the derived address, explorers index by it, and the raw key only appears in developer tooling.

The public key is what makes the whole ledger checkable. When a transaction is broadcast it carries a signature; every node uses the public key to confirm the signature is valid before including the transaction. No secret is exchanged in the process, which is the property that lets a global network agree on who owns what without trusting any participant. The same mathematics underpins every signature the ledger has ever verified.

It also draws the line for tracking. Everything a public key or an address can reveal, balances, history, positions, approvals, is already public. A tracker that works from addresses is reading what the chain publishes to everyone; it gains no authority over the funds and cannot lose any. Extended public keys, xpubs, take this a step further by exposing a whole account’s address sequence, with the privacy cost that implies.

TrueHold works from public addresses and never from private material. Paste an address and it is read; there is no key to hand over.

Chains differ in how they turn the public key into an address, which is why the same seed phrase yields a 0x string on Ethereum, a base58 string on Solana and a bc1 string on Bitcoin. The underlying idea does not change: the address is a public handle derived from a public key, safe to share, and everything about it can be read by anyone.