<p>Because bitcoin and all of its derivatives have addresses start with their own prefixes, I can  write a program that can tell between Litecoin, Namecoin, Bitcoin, and testnet addresses.</p>

<p>Imagine if you couldn't - lets say you see a *coin address on the website of an open-source project, and send some bitcoins to it. It turns out that it's actually a devcoin address. Of course, they could have clarified that it was a devcoin address, but that would take more than one character :)</p>

<p>It also reinforces the point that they're different coins.</p>

CC BY-SA 3.0
2016-08-09T18:54:32.103Z
"L"  is the prefix for a compressed pubkey ... or litecoin.   You can't use the prefix, only, to tell a damn thing.
Erik Aronesty
CC BY-SA 3.0
2016-08-09T23:51:12.990Z
@ErikAronesty Litecoin uses a version of 48, while Bitcoin uses 128 for private keys. An address parser can tell the difference, even if it starts with the same letter sometimes.
Nick ODell
CC BY-SA 3.0
2013-04-05T22:58:43.713Z
2013-04-05T22:58:43.713Z
Nick ODell
<p>If an address begin with "1" then it's a hash of a public key, "3" for a script hash, "5" for a private uncompressed key, etc</p>

<p>You can find a list of all prefixes here: <a href="https://en.bitcoin.it/wiki/List_of_address_prefixes">https://en.bitcoin.it/wiki/List_of_address_prefixes</a></p>

CC BY-SA 3.0
2013-04-13T04:55:57.877Z
I am not sure what "script hash", BUT I am asking here - http://bitcoin.stackexchange.com/questions/9678/what-is-script-hash-address-exactly-and-how-does-it-work :)
Karel Bílek
CC BY-SA 4.0
2019-06-17T18:30:18.973Z
This didn’t answer the “_Why?_”
Константин Ван
CC BY-SA 3.0
2013-04-05T22:33:56.707Z
2013-04-05T22:33:56.707Z
Nicolai
<p>The title is the question :)</p>

<p>All the addresses I have seen - from the very first block <a href="http://blockexplorer.com/b/0">http://blockexplorer.com/b/0</a> to the very last one <a href="http://blockexplorer.com/b/229850">http://blockexplorer.com/b/229850</a> all begin with "1".</p>

<p>Why is that? And - if it's really like that - why do we need the redundant number there and not just cut it and make the addresses 1 letter shorter?</p>

CC BY-SA 3.0
2013-04-05T21:51:18.577Z
I tried to read https://en.bitcoin.it/wiki/Technical_background_of_Bitcoin_addresses but I still don't see how the 01 suddenly appear in the RIPEMD hash. 00 is for the main network, I guess. But what for the 01?
Karel Bílek
<address>
Why do all addresses begin with "1"? Why can't we just delete it?
Karel Bílek
# Why do all addresses begin with "1"? Why can't we just delete it?

(Asked by: username_0 on 2013-04-05)

The title is the question :)

All the addresses I have seen - from the very first block <http://blockexplorer.com/b/0> to the very last one <http://blockexplorer.com/b/229850> all begin with "1".

Why is that? And - if it's really like that - why do we need the redundant number there and not just cut it and make the addresses 1 letter shorter?

**Tags:** address

> **Comments:**
> **username_0**: I tried to read https://en.bitcoin.it/wiki/Technical_background_of_Bitcoin_addresses but I still don't see how the 01 suddenly appear in the RIPEMD hash. 00 is for the main network, I guess. But what for the 01?  

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## 2 answers

### Answer by username_3 on 2013-04-05. Score: 16 | Accepted answer

If an address begin with "1" then it's a hash of a public key, "3" for a script hash, "5" for a private uncompressed key, etc

You can find a list of all prefixes here: <https://en.bitcoin.it/wiki/List_of_address_prefixes>

> **Comments:**
> **username_0**: I am not sure what "script hash", BUT I am asking here - http://bitcoin.stackexchange.com/questions/9678/what-is-script-hash-address-exactly-and-how-does-it-work :)  
> **username_4**: This didn’t answer the “_Why?_”  

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### Answer by username_1 on 2013-04-05. Score: 0

Because bitcoin and all of its derivatives have addresses start with their own prefixes, I can write a program that can tell between Litecoin, Namecoin, Bitcoin, and testnet addresses.

Imagine if you couldn't - lets say you see a \*coin address on the website of an open-source project, and send some bitcoins to it. It turns out that it's actually a devcoin address. Of course, they could have clarified that it was a devcoin address, but that would take more than one character :)

It also reinforces the point that they're different coins.

> **Comments:**
> **username_2**: "L"  is the prefix for a compressed pubkey ... or litecoin.   You can't use the prefix, only, to tell a damn thing.  
> **username_1**: @username_2 Litecoin uses a version of 48, while Bitcoin uses 128 for private keys. An address parser can tell the difference, even if it starts with the same letter sometimes.  

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