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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?
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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
This didn’t answer the “Why?” – Константин Ван – 2019-06-17T18:30:18.973
1 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 :)
can we get one form of address from another form ? i mean if my address starts from 3, can i get its address starting with 1 ? – AMB – 2017-07-20T20:24:36.770
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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.
"L" is the prefix for a compressed pubkey ... or litecoin. You can't use the prefix, only, to tell a damn thing. – Erik Aronesty – 2016-08-09T18:54:32.103
@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 – 2016-08-09T23:51:12.990
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 – 2013-04-05T21:51:18.577