Newbie Question - Significance of Wallet File?

[BittBurger]

So technically you never have to load up a wallet software to receive coins, after you've loaded it up once and determined your receiving address.

You can just make sure you save the receiving address and send any new coins to that address.

Then check the blockchain for the balance.

But that begs the questions:

1)  Where exactly are the coins? Are they in the wallet.dat file? Or are they on the block chain?

2)  If the blockchain is just a documentation of where the coins are, then the wallet.dat file is very important to keep. Should you always update the wallet.dat file then? Or never need to?

3)  It seems to me someone could hack the blockchain and simply change an address from "5" to "0" and it wouldn't matter what your wallet.dat file says. If that's the case then the wallet.dat file isn't the gold standard.  The blockchain is. See the overlap?

Thanks.

[hayek]

1.) No where. Not even on the blockchain. There is no actual file or data the is a bitcoin. It's just a record of entitlement in the blockchain

The blockchain is a ledger. When a block is mined think of it as an accountant writing a page of the ledger. As a reward for writing the page he receives the rewards + transaction fees. He then writes all of the queue'd transactions to the page in the ledger that came through since the last block was mined.

You're private key is stored in your wallet.dat. That key is used to identify you as the 'owner' of a denomination of BTC and is used to sign a transaction if you spend coins. The wallet balance is derived by scanning the block chain for transactions associated with you.


2.) If you lose your wallet.dat all coins associated with that key are useless now. You won't get them back. I encrypt my wallet.dat and I have a back up stored in a pw protected rar file off my main pc.

3.) Go ahead. You can make any change you want to your block chain. There's nothing you can do about the other people on the network. What you are talking about is covered under the 51% attack. If any one person or group were to obtain over 51% of the network hash rate they would be able to control block mining and it would fork the blockchain. Lots of information is posted about this. I recommended checking it out