The short answer: bitcoin has four address families in everyday use, and the prefix tells you which one you're looking at. 1… is Legacy (2009's original), 3… is Nested SegWit (the compatibility bridge), bc1q… is Native SegWit (today's default), and bc1p… is Taproot (the newest). All of them hold the same bitcoin on the same network — the difference is what your transactions weigh, and therefore what they cost.
The four families, side by side
| Type | Prefix | Since | Typical send* | Fee vs Legacy | Verdict |
|---|---|---|---|---|---|
| Legacy (P2PKH) | 1… | 2009 | ~226 vB | baseline | Works forever; expensive to spend |
| Nested SegWit (P2SH) | 3… | 2012/2017 | ~167 vB | ~26% cheaper | The compatibility bridge; fine, dated |
| Native SegWit (P2WPKH) | bc1q… | 2017 | ~141 vB | ~38% cheaper | The safe modern default |
| Taproot (P2TR) | bc1p… | 2021 | ~131 vB | ~42% cheaper | Cheapest & most private; rare send-support gaps |
*1 input, 2 outputs — the most common shape of a simple payment. Multi-input transactions widen the gap further: inputs are where old formats really bloat.
Why the prefix changes the price
Bitcoin fees are charged per virtual byte, and each address family locks coins with a different script — heavier or lighter to unlock. Legacy signatures sit fully inside the transaction body; SegWit moved them to a discounted "witness" area (that's the 2017 upgrade's whole trick); Taproot compressed things further with Schnorr signatures, which also make complex spends (like multisig) look — and cost — the same as simple ones. Same coins, same security model, lighter packaging.
The ancestors: P2PK and why Satoshi's coins confuse explorers
Before addresses existed at all, early rewards were paid to raw public keys (P2PK) — the format of 2009. Explorers don't credit those outputs to the derived modern addresses, which is why Satoshi's 1.1M BTC is invisible on address lookups and has to be tracked at the output level, the way our live watch does. Address types aren't trivia — reading them correctly is the difference between watching the real fortune and watching an empty page.
Questions people actually ask
Can I send bitcoin from an old address type to a new one?
Yes, freely — all address types live on the same network and interoperate. A payment from a 2011-era "1…" address to a Taproot "bc1p…" address is just a normal transaction. Migrating to a modern type only requires sending yourself the coins.
Are old addresses less secure?
Legacy addresses remain cryptographically sound. The practical differences are cost (they produce heavier transactions) and features (newer types enable multisig efficiency and better privacy). One nuance: reusing any address — old or new — is the real security and privacy mistake.
What happens if I send to the wrong address type?
If the address is valid, the coins arrive — type mismatches are impossible by construction, since the address encodes its own spending rules. The danger is a mistyped address; modern formats (bech32) have checksums that make typos overwhelmingly likely to be rejected outright by your wallet.
Which address type should I use today?
Native SegWit (bc1q…) is the safe modern default: cheapest common type, universally supported. Taproot (bc1p…) is slightly cheaper to spend and more private in some setups but a few old services still cannot send to it. Avoid creating new legacy addresses — they only cost you fees.