Help Make Me Understand How This Is Possible.

[Fivestar4everMVP]

first thing first, I want to apologize if the question below sound really noob, it is indeed noob but I really want to understand how this is done.

I am currently looking at this transaction history which supposedly is the first bitcoin to usd transaction.

I understand that a single address can send bitcoin to multiple addresses at a time using bitcoin core, and one single transaction hash(ID) will be generated for that transaction.

Now here is what I don't understand



In the screenshot above, you notice that the "Senders" 74 different addresses sent 50BTC each to "Recipients" 1 address, and this transaction has 1 transaction hash(ID).

Now, my question is, how is it possible for 74 (persons) addresses to send bitcoin to my (1) address, and all the 74 transactions put together will have one (1) transaction hash(ID)?.

[hosseinimr93]

Any bitcoin transaction can have multiple inputs and multiple outputs.
Assume that you have received two transactions and you have 2 UTXOs. Now, you can spend both UTXOs in a single transaction and there is no need to make two transactions.

Now, my question is, how is it possible for 74 (persons) addresses to send bitcoin to my (1) address, and all the 74 transactions put together will have one (1) transaction hash(ID)?.

That's not 74 transactions. That's a single transaction with 74 inputs.

[LoyceV]

how is it possible for 74 (persons) addresses to send bitcoin

It's one person with 74 addresses in 1 wallet.

[DannyHamilton]

It's not clear to me if that "74 senders" is a count of unique inputs or if it's a count of unique addresses used in 74 (or more) inputs.

For now, let's use an example of unique addresses.

A wallet is software that manages your transactions for you. Most good wallets allow you to generate as many receiving addresses as you like, and then the wallet software keeps track of all the bitcoins that are received using those addresses and shows you the total.

So,if your wallet generates 3 addresses (ABC, DEF, and GHI), and I then send 5 bitcoins to address ABC, 5 bitcoins to address DEF, and 5 bitcoins to address GHI, your wallet will show you that you have received (and have control over) a total of 15 bitcoins.  Those are still 3 separate outputs in the blockchain each being tracked separately by your wallet software.

Now, when you decide to spend those 15 bitcoins to purchase something from someone with address JKL, you tell your wallet to send 15 bitcoins to address JKL.

Your wallet creates a transaction with 3 inputs (the 5 bitcoins that were received at ABC, the 5 bitcoins that were recevied at DEF, and the 5 bitcoins that were received at GHI) and 1 output (to address JKL). It then provides 3 separate signatures (one on each input with the associated private key for your address where those bitcoins were previously received).  Those 3 signatures provide authorization for those 3 inputs to all be spent.

Then, some blockchain monitoring software run by blockchair takes a look at this transaction as it comes across the network, and it doesn't know for certain if all 3 of those addresses are from the same wallet (and therefore probably from the same person) or if they are each controlled by a different person with each person using special software to sign only their own input on the transaction. So, blockchair reports it as "3 senders" and leaves it up to you to decide for yourself if those 3 addresses are actually under the control of 1, 2, or 3 unique people

[BitMaxz]

It's not clear to me if that "74 senders" is a count of unique inputs or if it's a count of unique addresses used in 74 (or more) inputs.

Based on that transaction all of them are unique addresses with unique inputs. The blockchair explorer also includes multiple inputs in a single address under the sender but that transaction any address there does not have multiple outputs.

Take a look at this sample

[n0nce]

I recommend you have a look at LearnMeABitcoin's page about transactions. https://learnmeabitcoin.com/beginners/transactions

As you can see, even if you only ever bought Bitcoin once, which is deposited in a single address, the moment you spend it, you generate 2 outputs, except if you spend it in full. Because obviously, you want your change back!

[NotATether]

Also, depending on your wallet software, it might try to send all your inputs (all the instances of you receiving bitcoins at any given time), "spending" them, and returning to your address the remainder, that you didn't intend to send, as one large "change" amount of Bitcoin.

[Fivestar4everMVP]

Thank you everyone for your inputs, I really appreciate your time and efforts.
Unfortunately, I am currently out of sMerits, but I promise to come back here as soon as a gather some.

I wanna thank @DannyHamilton specially for taking out time to explain this in full details and with illustrations, the example used  helped me understand exactly what I wanted to understand, thank you so much.

I have no more question to asked concerning this topic since I now perfectly understand how such a transaction is possible, so I guess I should just lock the thread now.