What is a BTC address and why do you need it? If you are a first-time cryptocurrency user, you need to have these questions answered before you start sending or receiving bitcoin.
We are here to help!
It is a unique identifier you need to send or receive your digital funds. They sometimes compare it with an email address you give people if you want to hear from them.
A correct BTC address looks like a string of 26 – 34 letters and numbers. It always starts with 1, 3 or bc1 prefix. There are different address formats, we will be dealing with them later in this article.
Below are some basics you need to know about a Bitcoin address.
Now, let’s see how it all works in theory and practice.
Imagine, you owe your friend Bob 1 BTC and want to send this amount to him. Bob has a wallet app installed on his mobile device. What you guys do next?
Ok, and what happens if you accidentally send more BTC than you owe? Remember, Bob cannot return the extra coins to you, as there’s no such option. No, he should not use the address you gave him when you were borrowing 1 BTC from him. The reason is simple — Bob cannot be sure you still use it. If you don’t, the money may get lost somewhere in cyberspace.
So, the best option for you would be to go to your wallet and create a brand-new address for Bob. Then you provide it to him for one-time use.
For security reasons. You know that in a blockchain network all the confirmed transactions enter the distributed public ledger. ‘Public’ means that anyone can view the records with your public address. If you use it repeatedly, it would be rather easy to follow your financial activities. In some cases, it’s possible to link them to your real identity.
To prevent this from happening, you’d better use a new address for every occasion.
Sometimes people think these two things are the same, and it causes confusion. Let’s make it clear.
Your BTC address, as the name suggests, is like an email address.
People send you stuff using it. On the technical level, it’s a hash of your Public key.
Hash is a product of a cryptographical function that always returns you a piece of code of a certain length, no matter what you input. To get a BTC address, we hash a Public key first with SHA256 function and then apply RIPEMD160 function to the result. Then we encode the result as Base58 format to make it more readable and human-friendly.
If it seems too difficult, you can see the Bitcoin address as a shortened version of your Public key. Any such version is different — the probability of generating two identical addresses is almost zero.
Thus, the Public key is the thing a wallet app uses to create an indefinite number of new addresses.
Continuing the analogy, a wallet app is your ‘email client’. The private key (the one you should keep secret) is your password.
Before sending your bitcoins, you can check if the address you use is valid. First, you check the length of the string — as we mentioned, it must be between 26 and 34 characters and begin with 1, 3 or bc1. Also, we recommend you to use a special online tool.
Note that most wallet apps should check the address for you automatically. If you insert an incorrect (not long enough, containing some invalid characters, etc.) address into the Recipient field, the app will not allow you to send.
IMPORTANT: If the address you use is valid, it means you can send money to it. It does not mean that the wallet is active (actually used by someone).
If you manage your funds collectively, you may want to create a multi-signature Bitcoin address using a combination of multiple private keys.
A multi-signature address has a prefix 3, as it’s a newer technology. You may think of such an address as of a check issued for two persons. You cannot cash this check unless both parties (you and your partner, friend, spouse, colleague) authorize this operation.
The person responsible for a multi-signature address generation must decide in advance on the exact number of private/public keys needed for the purpose. Once you have created such an address, you cannot change these details. If you need to do it, you start the process anew.
You can generate a multi-signature address without using a third-party service, by executing a special command in the Bitcoin Core client. An easier way would be to use a multi-signature wallet provider service like Electrum.
A multi-signature BTC wallet is a good option for startups with several co-founders who don’t want to put one person in charge of their common funds.
A correct BTC address has the following features:
There are three BTC address formats: P2PKH, P2SH, and bech32. Normally, they don’t come into conflict, though few wallet providers and exchanges support all of them. Let’s see how these formats are different from each other and what the pros and cons they feature.
If you are dealing with P2PKH format, your BTC address starts with 1. It was the format BTC used originally, so they also call it ‘Legacy’.
The abbreviation P2PKH stands for ‘Pay-to-Pubkey Hash’. It means ‘Pay to a Hash of the Public Key’.
If you send bitcoins from a legacy address, you are likely to pay a higher fee as such a transaction is larger in size. Also note that P2PKH and SegWit formats are not compatible, but you can send your bitcoins from a Segwit address to a P2PKH address.
Any address of this format begins with a 3. The name P2SH means ‘Pay to Script Hash’. You lock your bitcoins to the hash of the script. To unlock them, you need a special unlocking script (the original script + some additional data).
Such an address feature wider functionality than a legacy address. It’s often used for multi-signature BTC wallets we talked about earlier.
Without diving deeper into technical details too complicated for a beginner, it’s the most popular type of Bitcoin address. You can use P2SH to send you digital funds to an address of any format. It ensures cheaper transactions and a slightly higher level of privacy.
A bech32 address is longer than any other, as it begins with the ‘bc1’ prefix. Most wallets (both soft- and hardware ones) support this native SegWit format.
On the downside, few exchanges do it. Most often, your exchange will allow you to send funds to a bech32 address. The problem is that you are unlikely to receive anything using it.
What is a Bitcoin address?
It’s a unique identifier you use to send and receive digital funds.
What does a Bitcoin wallet address look like?
It looks like a long string of characters (uppercase and lowercase letters and digits) and starts with 1, 3 or bc1 prefix. Also, a BTC address can be represented as a QR code.
How long is a Bitcoin address?
A correct BTC address contains 26 – 34 characters. The number of characters depends on the format used.
How many formats are there?
There are three formats of Bitcoin addresses. They are P2PKH, P2SH, and Bech32. They start at 1, 3 and bc1, respectively.
Is BTC address identical to Public Key?
No, it’s not. A Bitcoin address is a hash of your Public Key.
How many times can I re-use the same BTC address?
It’s better not to reuse it at all. You should create a brand-new address for every BTC transaction. It helps to protect your privacy and prevent other users from tracking your financial activity in the blockchain network.