Query regarding BitCoin wallet money

[bitcoin_geek]

Please pardon me for asking such a basic question.

Who checks that for a particular transaction, your wallet has sufficient money?

If Person A has to send Person B 5 BitCoins, which process validates that Person A wallet has the required amount for the transaction?

Thanks in advance!

[Senor.Bla]

Please pardon me for asking such a basic question.

Who checks that for a particular transaction, your wallet has sufficient money?

If Person A has to send Person B 5 BitCoins, which process validates that Person A wallet has the required amount for the transaction?

Thanks in advance!

That is actually a good question.
Miners verify transactions and put them in a block they try to mine. This means that every confirmed transaction is checked. So how do they check it?
The blockchain is a ledger that contains all transactions. There you can see when a coin was created and if a coin was spend and to which address it was spend. If there is no further address to which the coin was send, then it is still in the current address.
There is also a list of all addresses that hold unspent Bitcoins, so it is easy to check.  

edit: also i think all wallets check if you have sufficient funds.

[Coinster]

That is actually a good question.
Miners verify transactions and put them in a block they try to mine. This means that every confirmed transaction is checked. So how do they check it?
The blockchain is a ledger that contains all transactions. There you can see when a coin was created and if a coin was spend and to which address it was spend. If there is no further address to which the coin was send, then it is still in the current address.
There is also a list of all addresses that hold unspent Bitcoins, so it is easy to check.  

edit: also i think all wallets check if you have sufficient funds.

This is a good and simple explanation.

If someone wants a little more detailed answer here goes. The Bitcoin network is made up of two types of user on a technical level: mining nodes, and full nodes. Both these types user verify all transactions. When a user wants to send bitcoin they make a transaction and announce it to the network using their wallet software. The network of nodes pass transactions to each other. Mining nodes create blocks of transactions (about every 10 minutes) and have the special ability of deciding the order of transactions (e.g. did Bob send a transaction to Suzy or Alice first if they conflict).

When a miner makes a block containing a transaction, that transaction is said to be 'confirmed', meaning the network recognizes that transaction as valid. Due to special circumstances it's possible that a block of confirmed transactions will not remain valid. However, the more blocks that are built on top of that block, creating the blockchain, the less the chance that block might become invalid. As a user your confidence that you actually got paid rests on the number of confirmations a transaction has (the number of blocks built with and on top of the block containing it). People are advised to seek at least 1 confirmation, but for better security 6 confirmations or more.

edit: also i think all wallets check if you have sufficient funds.

Wallets check this if they are full-node wallets. Bitcoin Core is currently the most popular full-node wallet software. Web wallets that let people use bitcoin via web interface like Blockchain.info usually run full-node software in the background.

[AngelSky]

Please pardon me for asking such a basic question.

Who checks that for a particular transaction, your wallet has sufficient money?

If Person A has to send Person B 5 BitCoins, which process validates that Person A wallet has the required amount for the transaction?

Thanks in advance!

Every transaction will transfer via each blocks with the help of miners to reach the receiver destination. Nowadays in blockchain.info minimum fees amount has been increased for every transaction. Normally in a transaction, Once you have receive the first confirmation you can confirm that you will receive bitcoin in next confirmations.

[Velkro]

Who checks that for a particular transaction, your wallet has sufficient money?

Well, your "wallet ballance" is just private key with transactions not yet spend. You have for example 1 BTC. If you spend that, all money in this transaction must be used. So you could sent someone 0.5 BTC but rest of it 0.5 BTC must be sent to ur own new address as change (we skip transaction fee here).
So miners see if 0.5 + 0.5 = 1 if yes, then he accepts ur transaction, if not transaction is invalid. Simple math.

[bitcoin_geek]

Please pardon me for asking such a basic question.

Who checks that for a particular transaction, your wallet has sufficient money?

If Person A has to send Person B 5 BitCoins, which process validates that Person A wallet has the required amount for the transaction?

Thanks in advance!

That is actually a good question.
Miners verify transactions and put them in a block they try to mine. This means that every confirmed transaction is checked. So how do they check it?
The blockchain is a ledger that contains all transactions. There you can see when a coin was created and if a coin was spend and to which address it was spend. If there is no further address to which the coin was send, then it is still in the current address.
There is also a list of all addresses that hold unspent Bitcoins, so it is easy to check.  

edit: also i think all wallets check if you have sufficient funds.

So basically wallets check whether you have sufficient coins for the transaction or not.

And what miners does is 'validate' the transaction (encrypt the transaction data hash) by calculating crypto-graphic hash functions.

Am I right?

[bitcoin_geek]

Who checks that for a particular transaction, your wallet has sufficient money?

Well, your "wallet ballance" is just private key with transactions not yet spend. You have for example 1 BTC. If you spend that, all money in this transaction must be used. So you could sent someone 0.5 BTC but rest of it 0.5 BTC must be sent to ur own new address as change (we skip transaction fee here).
So miners see if 0.5 + 0.5 = 1 if yes, then he accepts ur transaction, if not transaction is invalid. Simple math.

So is this verified by the miner? I thought he only validates the transactions by calculating crypto-graphic hash functions.

[Senor.Bla]

Please pardon me for asking such a basic question.

Who checks that for a particular transaction, your wallet has sufficient money?

If Person A has to send Person B 5 BitCoins, which process validates that Person A wallet has the required amount for the transaction?

Thanks in advance!

That is actually a good question.
Miners verify transactions and put them in a block they try to mine. This means that every confirmed transaction is checked. So how do they check it?
The blockchain is a ledger that contains all transactions. There you can see when a coin was created and if a coin was spend and to which address it was spend. If there is no further address to which the coin was send, then it is still in the current address.
There is also a list of all addresses that hold unspent Bitcoins, so it is easy to check.  

edit: also i think all wallets check if you have sufficient funds.

So basically wallets check whether you have sufficient coins for the transaction or not.

And what miners does is 'validate' the transaction (encrypt the transaction data hash) by calculating crypto-graphic hash functions.

Am I right?

No wallet that i know will make an transaction without checking if you have sufficient funds. You can still create scenarios where a wallet is not up to date or i prepared the transaction a week ago and didn't send it yet (but spend the money otherwise). But this checking is a kind service to the user (so he knows how much he has to spent) not the job of a wallet. The job of a wallet is to create the transaction, to fill out the form so to say. And then tell it to the network. The network and by that i mean the nodes and miners will check it. BTW miners are also nodes. Nodes are basically miners that lave the mining part out. Those nodes and miners job is to check if a transaction is valid or not. They will simply reject your transaction if it is not and you will have your feedback quickly.
So what extra work do miners? They simply take a bunch of those unconfirmed (but verified through the nodes) transactions flying around and put them in a box (confirming them). Once they are in a box they are considered save and all agreed to it.