Firstbits makes Bitcoin addresses easy to remember and share. A firstbits address uniquely identifies a Bitcoin address, usually in less than 7 characters.
When you enter a Bitcoin address:- We convert any uppercase letters in the address to lowercase.
When a firstbits address is entered we return the Bitcoin address in which it first appears.
A firstbits address will always return the same Bitcoin address because new addresses are only added to the end of the block chain. Note that firstbits.com waits until 7 confirmations to return firstbits for a given address. In rare cases, it may take longer than this for your address to appear in the database.
You create a new address, 1Kk5kFbh1dWYHY214tTx2ngUjsESfvLdV3, and make a small payment to it so that the address will be recorded in the block chain. You enter it at firstbits.com and get the firstbits address 1kk5k. Now you can give this to a friend or client and they can look up your full address.
If your Bitcoin address is 1Kk5kFbh1dWYHY214tTx2ngUjsESfvLdV3 and your firstbits address is 1kk5k, you can give 1kk5kf or 1kk5kfb to reduce the chance that a typo will lead to a mistaken payment.