Topic: How do I read the blockchain? (Read 551 times)

You are referring to, where you can be tracked from ip if you are using an online wallet that will be listed is the ip of the online wallet service but I believe they do have other data to track your ip but it was not published.

I haven't seen any that really impress me much yet.

blockchain.info is probably one of the most popular, but they also tend to have bugs and downtime that can be frustrating at times.  They have frequently ended up on a bad fork, and when that happens it has taken them up to a few days to fix the problem.

I suspect that most of their popularity comes from their choice of name and the fact that a lot of people don't realize that blockchain.info is not "the blockchain".

You may also want to look at:
http://btc.blockr.io/
https://blockexplorer.com/
https://live.blockcypher.com/btc/


I don't trust any of them.  I run my own full node, and when I want transaction details, I get them from my node.

When I need/want to link someone to information about a transaction, I will typically first verify that what I see at blockchain.info matches what I see on my own node.  Then I'll link to blockchain.info, not because I trust them, but because the link is recognized by most people so they won't be concerned about clicking on it.

Thank you for the detailed explanation, it was exactly what I was hoping for when I posted my questions. Ref your quote above, is there a site that is generally trusted the most in terms of being able to interpret transactions from the blockchain? Or simply put, which site do you trust the most when looking for transaction details?

You are mistaken.

That link does not show you "the blockchain".  That link shows you a web page created by a private company that has chosen to name themselves "blockchain.info".  blockchain.info is NOT "the blockchain".  That company collects their own copy of the blockchain (as well as other information from the bitcoin network) and then interprets that information and creates web pages and charts that attempt to explain what they think is happening.  They aren't always correct.


Again, that link verifies only what the company called "blockchain.info" has interpreted from the blockchain.  In this case it appears that they've done a misleading job of showing you some of the technical details behind how bitcoin transactions work at the protocol level, but a pretty good job of interpreting that technical information into concepts that might feel more familiar to users.

What you see there is only 1 transaction.  On the left it shows the addresses that previously received the outputs that are being spent by the transaction and what the value of each of those outputs was. On the right it shows the two addresses that received the value that was supplied to the transaction and how much of that value was received by each address.

I assume that 1NybeKPyqVv8d9brkSTubgk5NynJy3h4hw is your address.  It looks like the transaction spent two outputs valued at 0.119 BTC and 0.3017804 BTC for a total value supplied to the transaction of 0.4207804 BTC.  Of that value, 0.38603733 BTC was assigned to an output with your address.  That left 0.03474307 BTC unaccounted for.  The transaction assigned 0.03424307 BTC of that remaining amount back to the address 19Kwfve8NLCnu6KJoAG2Jhg1knWmgTchEu (the same address where the value came from). The last remaining 0.0005 BTC that are not accounted for in the transaction become transaction fees for the miner that first placed the transaction into a block on the blockchain.


It is only 1 transaction, and it is from the perspective of blockchain.info's interpretation of the transaction.  The transaction was supplied with value (which can be seen on the left) and re-assigned that value to new addresses (which can be seen on the right).


Yes.


Then you are usually looking at blockchain.info's interpretation of what activity a given address has had on the bitcoin network instead of looking at blockchain.info's interpretation of a single transaction.


More specifically, the blockchain.info company has not yet seen any transactions on the bitcoin network that spend that specific transaction output.

If they had seen such a transaction, they would have changed the label to "spent" even if the transaction was not yet in the blockchain.


Where it was sent to?  That depends on what you mean.

It is possible to see what transaction is funded with those bitcoins.  It is therefore possible to see each of the outputs that are created by the transaction and how much value each of those outputs receives.  If the outputs are standard P2PKH or P2SH outputs, then it will be possible to see what address those new outputs will be associated with.  If ownership of any of those addresses is known, then it would be possible to know who the bitcoins are sent to.


At the protocol level, you can't spend small parts of a transaction output.  You have to spend the entire output all at once.  Therefore, your wallet software will create a transaction that spends the entire 0.38603733 BTC output to fund the transaction.  It will then create an output for this new transaction and assign the small amount you are sending to this output.  The output will have the address you are sending to.  Then the wallet will subtract the transaction fee (if you include any) from the remaining value.  If there is any value remaining after that, the wallet will create another output and assign the remaining value to it.  This second output will be assigned to an address that your wallet has control over.  Depending on the wallet software that you use, the wallet might create a brand new address that it doesn't tell you about, but it keeps track of internally, or if might re-use an address that you have created in the wallet in the past.

It's rather simple... What you see here is somebody using 2 inputs (~0.11 and ~0.3 BTC) to create 2 outputs: ~0.38 BTC to you, and 0.03BTC is change that is probably sent back to the sender's wallet.

A sender cannot use part of an input, he has to use everything. The part of the inputs that isn't used to generate outputs is the miners fee, and is "lost" (actually, it's an incentive for the miner to add your transaction to a block).
This is why usually, you'll see one or more inputs (the sum of the inputs has to be larger than or equal to the amount you wish to send + the fee) and 1 or more outputs (one output to the receiver, one output to send the change back to the sender).

The rest of your assumptions are correct, tx stands for transaction, address for address, unspent means the output is not yet used as input for a next transaction.

So I did a nice trade today and received my first decently sized chunk of BTC (compared to the faucets I've usually been doing) for around $200 BTC and when I clicked the link to verify the transaction on the blockchain, it seems to be showing another transaction apart from mine:

https://blockchain.info/tx/f1478eda31c08d76b4f6daf0d7bdda64eba09556d0f4ca096ea09c3c6f1283e2

Can you tell me... is this from the perspective of the sender and are both transactions from the same sender? What does the /tx/ in the URL stand for? Transaction? I usually see the /address/ URL and I'm not used to this one. Also, when it reads "unspent" I'm assuming that the blockchain has tracked that I have not spent the BTC yet. Is there a way to further track which address the money was sent to once I spend it? What if I spend small portions of it... how does that get tracked?