Bitcoin has no physical form. The project's own FAQ calls it "a completely digital money": bitcoins "exist as records on the blockchain", and a wallet holds the keys that control them, not the coins. In practice you see Bitcoin in four ways: an address (a string of letters and numbers such as bc1q…), a balance in a wallet app, a QR code, or a transaction entry on a public block explorer. The gold coins with a ₿ in news photos are stock images. The few physical coins that did hold real bitcoin, mainly Casascius coins from 2011 to 2013, are collectors' items. They show how Bitcoin works but are not how people use it.
What a bitcoin actually is
On the blockchain, a bitcoin amount is an output of a transaction, locked to a script that only the holder of the matching private key can unlock. The Bitcoin developer glossary defines a private key as "the private portion of a keypair which can create signatures that other people can verify using the public key." Owning bitcoin means controlling that key, not holding an object.
Two numbers set the rules:
- 21 million. Bitcoin.org says "only 21 million bitcoins will ever be created."
- 100,000,000 satoshis per bitcoin. Bitcoin can be divided to eight decimal places, so 0.00000001 BTC (one satoshi, or "sat") is the smallest unit.
The ₿ symbol and the logo
The sign ₿ has its own Unicode code point, U+20BF BITCOIN SIGN. It arrived in Unicode 10.0, released on 20 June 2017, so current phones and computers can show it as ordinary text. The usual ticker is BTC.
According to Decrypt's history of the logo, the first logo in early 2009 was a gold coin stamped "BC". In February 2010 Satoshi Nakamoto changed it to a "B" with two vertical strokes. In November 2010 a forum user known as "bitboy" posted the orange circle with a tilted white "B" to the public domain, and that version is still in use. These dates come from press histories, not from a primary record.
What a Bitcoin address looks like
An address is the closest thing Bitcoin has to a visible face. It is like an account number, except that anyone can look up its history. Mainnet addresses come in four common forms:
| Starts with | Type | Defined in |
|---|---|---|
1 | P2PKH (legacy) | Base58Check format |
3 | P2SH (script hash, often used for wrapped SegWit and multisig) | Base58Check format |
bc1q | SegWit version 0 (P2WPKH, P2WSH), Bech32 encoding | BIP 173 |
bc1p | SegWit version 1 (Taproot), Bech32m encoding | BIP 350 |
What to know before you copy one:
- Every address has a checksum. The Bitcoin Wiki says some characters exist only as a checksum, so wallet software rejects most typos instead of sending funds to a wrong address.
- Case matters for old formats. Legacy addresses are case-sensitive. Bech32 addresses are not. Copy and paste addresses instead of typing them, and check them against the full string, not only the prefix.
3does not always mean SegWit. P2SH addresses can wrap any script, so the old label "SegWit (P2SH)" is too narrow.- The character after
bc1shows the witness version. BIP 350 keeps Bech32 for version 0 (bc1q) and uses Bech32m for version 1 and up, which is why Taproot addresses start withbc1p.
Does this physical bitcoin hold any bitcoin?
Answer four questions about a coin or bar to see whether it can still control bitcoin on the blockchain.
Does the coin or bar come with a private key, such as a paper slip sealed under a hologram?
- Yes, it has a sealed private key → next question
- No, it is plain metal → A souvenir, not bitcoin
- I am not sure → next question
Is it an original Casascius coin from the 2011 to 2013 series, rather than an item sold after sales of loaded coins stopped in November 2013?
- Yes, an original 2011 to 2013 coin → next question
- No, or I cannot tell → A souvenir, not bitcoin
Is the tamper-evident hologram intact, with no honeycomb pattern showing?
- Yes, it is intact → next question
- No, the honeycomb pattern shows → Opened: the key may have been used
When you search the coin's published address on a block explorer, does it show an unspent balance?
- Yes, there is an unspent balance → The on-chain balance is still there
- No, the funds were moved → Empty, even if it looks original
With no private key that controls a verifiable on-chain balance, the item holds no bitcoin. Most coins sold today are decorative metal, and items Casascius sells now contain no bitcoin.
A visible honeycomb pattern means the hologram was peeled and someone has seen the private key. Check the published address on an explorer: owners often sweep the funds after opening a coin.
The address shows the bitcoin was moved, so the coin no longer controls any. A coin can be peeled, swept and given a replacement hologram, which is why the explorer check matters more than its looks.
An intact hologram and an unspent balance on the published address are the checks the article describes. They cannot prove the key under the hologram is the original, so buy only from sellers you can verify, and never paste a private key into any website.
This follows the article's checks only: it cannot authenticate a coin, detect a replaced hologram, or say what a coin is worth.
What Bitcoin looks like on a block explorer
A block explorer such as mempool.space or blockstream.info shows the raw public record. You can paste in an address, a transaction ID or a block number.
Block view. Blocks are numbered from zero. Mempool.space reported a chain tip at block height 973,070 on 25 October 2026. The network aims for one block about every ten minutes: the developer documentation says difficulty is recalculated every 2,016 blocks against an ideal of 1,209,600 seconds (two weeks), which works out to 600 seconds per block.
Transaction view. Each transaction shows its ID (a 64-character hexadecimal hash), its inputs and outputs, the amounts in BTC, the fee and the number of confirmations.
The first block. Block 0, the genesis block, has a timestamp of 3 January 2009, 18:15:05 UTC. Its only transaction is the generation transaction, which pays 50 BTC directly to a public key (a P2PK output). Explorers show that key as the address 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa. On 25 October 2026 mempool.space listed 81,058 incoming outputs to that address, totalling 57.6875 BTC, with nothing ever spent. Most of those outputs are later payments that people sent to it.
What Bitcoin looks like in a wallet
A wallet app is how most people see Bitcoin day to day. Wallet layouts differ, but the main parts are the same:
- Balance. An amount in BTC or sats, usually next to a value in local currency at the current price.
- Receive screen. An address and a QR code. Many wallets put the address in a
bitcoin:link as defined in BIP 21 (since superseded by BIP 321). That link can also carry an amount, a label and a message, which lets a payer scan a QR code instead of typing. - History. Sent and received transactions with time, amount, fee and confirmation status.
A hardware wallet is a small device that keeps private keys offline and signs transactions. The bitcoin is still on the blockchain, not inside the device. If the device is lost, the funds can be recovered from the backup recovery phrase. If someone else gets the recovery phrase, they control the funds.
Physical bitcoins: Casascius coins and souvenirs
How Casascius coins worked
The best-known physical bitcoins were made by Mike Caldwell ("Casascius") of Sandy, Utah. According to the Bitcoin Wiki, the first 1 BTC brass coins appeared in September 2011. Each coin held a paper slip with a private key under a tamper-evident hologram. Peeling the hologram shows a honeycomb pattern, so anyone can see the coin has been opened. Later series included silver rounds, gold-plated coins and gold-plated bars of 100, 500 and 1,000 BTC.
The Bitcoin Wiki says the Financial Crimes Enforcement Network (FinCEN) told Caldwell that making loaded coins made him a money transmitter, which required federal registration and probably state licences. His own site says: "As of Nov 27, 2013, I suspended sales of items that contain digital bitcoins." Items he sells now contain no bitcoin.
How many were made: one collectibles outlet, citing a third-party Casascius analysis tool, puts the total at about 27,675 coins loaded with more than 90,000 BTC. This comes from a single source, and other reports give slightly different counts.
What they sell for and what happens to them now
- Auction prices. On 3 November 2023, Heritage Auctions sold 250 NGC-graded Casascius coins (150 of 1 BTC and 100 of 0.5 BTC) for $7,198,200 including buyer's premium, according to NGC. The top two coins in that sale each fetched $43,200. The old version of this article dated that result to late 2024, which was wrong. A 2013 1 BTC coin graded MS 68 sold for $78,000 in a Heritage sale on 28–29 February 2024, NGC reported.
- Redemptions. Owners still peel coins open and move the bitcoin. On 3 June 2026, Decrypt reported that a 25 BTC Series 1 coin, created in December 2011, had been peeled and its key swept on-chain, moving about $1.78 million. Citing Casascius Tracker data, Decrypt said 236 of the 345 coins in that 25 BTC batch had been redeemed. This rests on one news report and the tracker it cites.
Souvenir coins are not bitcoin
Most "Bitcoin coins" sold today are decorative metal with no private key attached. A simple test applies to any physical bitcoin: if it has no private key that controls a verifiable on-chain balance, it holds no bitcoin. Even an original Casascius coin can be empty if someone peeled it, swept the funds and replaced the hologram. Check the coin's published address on an explorer, and buy only from sellers you can verify.
How to see real bitcoin yourself in five minutes
- Open a block explorer such as mempool.space.
- Search for block
0to see the genesis block and its generation transaction. - Search for the latest block to see current transactions, fees and sizes.
- If you have a wallet, copy its receive address and paste it into the explorer. Everything that address has received and sent is public.
- Remember that the explorer only shows public data. Never paste a private key or recovery phrase into any website.
Limitations: figures from block explorers and auction reports are as of the dates given, and the Casascius totals come from a single third-party estimate.
