What Are Bitcoin Addresses?

What Is a Bitcoin Address?

A Bitcoin address is a string of letters and numbers that tells others where to send bitcoin. You share it the way you would share a bank account number or an email address. Anyone who knows your address can send you bitcoin, but they cannot touch your funds without your private key.

What a Bitcoin address is not, however, is a fixed account sitting on the blockchain. It is closer to a set of instructions that tells the network how the recipient wants to receive funds and under what conditions those funds can later be spent.

How an Address Is Created

Every Bitcoin address originates from a private key. That private key generates a public key through a mathematical process called elliptic curve cryptography. The public key then goes through two hashing functions in sequence, SHA-256 followed by RIPEMD-160, to produce the address.

This derivation only works in one direction. Anyone can go from private key to address, but nobody can reverse the process and extract a private key from an address. That one-way property is the foundation of Bitcoin security.

A checksum is also built into the address itself. If you mistype a single character, the checksum will catch it and the wallet software will reject the address before any funds are sent.

The Four Address Formats

Bitcoin has gone through several address format upgrades since it launched in 2009. Each format reflects a different underlying script standard, which affects transaction size, fees, and features. The table below compares the four formats currently in use.

Legacy (P2PKH)

The original format, in use since Bitcoin launched in 2009. Legacy addresses start with the number 1 and use a character set that deliberately excludes ambiguous characters such as the letter O and the number 0.

Legacy is still fully supported across the network, but it produces the largest transactions and therefore the highest fees. There is no technical reason to choose it today unless a specific counterparty requires it.

Example: 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa

Nested SegWit (P2SH-P2WPKH)

Introduced alongside the SegWit upgrade in 2017 as a compatibility bridge. Nested SegWit addresses start with the number 3. The format packages the newer SegWit logic inside a traditional script shell so that older wallets can still send to it.

Fees are lower than Legacy, but the format exists mainly for backward compatibility. If your wallet and your counterparties both support Native SegWit, there is no practical reason to use Nested SegWit.

Example: 37sfXRaSVnTXHP751Na7ZrfyzST1FHakCv

Native SegWit (P2WPKH)

The current recommended standard for most users. Native SegWit addresses start with bc1q and use the Bech32 encoding, which offers better error detection than older formats.

SegWit moved signature data out of the main block into a separate structure, freeing up space. The network prices that reclaimed space favorably, which translates into fees that are roughly 30% lower than Legacy on comparable transactions. Support across wallets and exchanges is now widespread.

Example: bc1qnj2502g4eeu9h2pp669xxl6vkseepmgrfjgx6q

Taproot (P2TR)

The newest format, activated in November 2021. Taproot addresses start with bc1p and use the updated Bech32m encoding. The format introduces Schnorr signatures, which are smaller and more efficient than the previous ECDSA signatures.

Taproot transactions look identical on the blockchain regardless of complexity, which improves privacy for all users. For someone who regularly consolidates many smaller bitcoin holdings into one transaction, Taproot fees can be lower than Native SegWit.

Wallet support has grown steadily since 2021, but adoption at exchanges and brokers remains incomplete. Native SegWit is still the safer default for most people today.

Example: bc1psvs8lx0kz3dl5nfnfkdjl3dy4vw3p34y97ytqt34hcapjeryn0gqg6njml

Address Reuse and Privacy

Modern wallets generate a fresh receiving address after each incoming transaction. This is not a bug. It is a deliberate privacy feature.

Bitcoin's blockchain is public and permanent. If you reuse the same address repeatedly, anyone can link all those transactions together and build a complete picture of your activity. A fresh address for each payment breaks that trail.

Your old addresses do not expire. Every address your wallet has ever generated remains valid and is still linked to your wallet. The new address is simply the one your wallet recommends you use next.

Which Format Should You Use?

For most users, Native SegWit is the right choice today. Fees are low, compatibility is high, and the format is well established.

Taproot is worth considering if your wallet supports it, particularly if you tend to accumulate many small incoming transactions over time. The fee advantage is most visible when a transaction has more inputs than outputs.

Legacy and Nested SegWit serve no practical purpose for new wallets. If your current wallet only offers these formats, it may be time to look for a more modern alternative.