# Private keys

A private key is a secret 256-bit number that controls your bitcoin. Learn what it looks like, how it creates addresses and how to keep it safe.

Canonical page: https://mybitcoinexplorer.com/learn/private-keys
Topic: Keys and addresses
Published: 2026-10-29
Updated: 2026-10-30


## A very big secret number
A private key is a randomly chosen number between 1 and about 1.16 × 10^77, roughly the number of atoms in the observable universe. Written in [hex](https://mybitcoinexplorer.com/learn/hexadecimal) it's 64 characters:

~~~
e9873d79c6d87dc0fb6a5778633389f4453213303da61f20bd67fc233aa33262
~~~

(An example only. Never use a key or seed you have seen published.)

## What it does
Your private key produces your [public key](https://mybitcoinexplorer.com/learn/public-keys) and your [addresses](https://mybitcoinexplorer.com/learn/bitcoin-addresses), and it creates the [signatures](https://mybitcoinexplorer.com/learn/digital-signatures) that authorise spending.

> Diagram: Everything flows one way from the private key — *Private key: secret → (one-way)Public key: shareable → (hash)Address: give to payers

You can share your public key and addresses safely. Nobody can work backwards to your private key. See [Elliptic curve cryptography](https://mybitcoinexplorer.com/learn/elliptic-curve-cryptography).

## Not your keys, not your coins
Whoever has the private key controls the coins: there is no password reset. In practice, wallets don't show you raw private keys. They back up everything with a [seed phrase](https://mybitcoinexplorer.com/learn/seed-phrases-bip39) from which all your keys are derived.

## How to keep it safe
- Let a reputable wallet generate it. See [Randomness and entropy](https://mybitcoinexplorer.com/learn/randomness-and-entropy).
- Keep the seed phrase offline, on paper or metal.
- Consider a [hardware wallet](https://mybitcoinexplorer.com/learn/hardware-wallets) so keys never touch an internet-connected computer.


## Scams that target your keys
- **Fake support** asking for your seed phrase "to verify your wallet".
- **Fake wallet apps** in app stores that send your seed to the attacker.
- **"Validation" websites** asking you to type your seed.
- **Clipboard malware** that swaps an address you copied for the attacker's.

No genuine wallet, exchange or explorer, including MyBitcoinExplorer, will ever ask for your private key or seed.


## Key takeaways

- A private key is a secret random 256-bit number.
- It controls the coins: anyone who has it can spend them.
- Public keys and addresses come from it, but can't reveal it.

## Common questions

### Can two people get the same private key?

With proper randomness, the chance is effectively zero.

### Where is my private key stored?

Inside your wallet software or hardware wallet, derived from your seed phrase.

### Can someone guess my private key?

Not if it was created with proper randomness; the number of possibilities is astronomically large.

### What happens if I lose my private key?

Without the key or a seed backup, the bitcoin it controls can't be spent by anyone.

## Related lessons

- [Public keys](https://mybitcoinexplorer.com/learn/public-keys)
- [Seed phrases (BIP 39)](https://mybitcoinexplorer.com/learn/seed-phrases-bip39)
- [What is a Bitcoin wallet?](https://mybitcoinexplorer.com/learn/what-is-a-bitcoin-wallet)
- [WIF private key format](https://mybitcoinexplorer.com/learn/wif-private-key-format)