Conducting transactions on the blockchain isn’t always easy. Especially at first! But there are certain sites that help us navigate the blockchain, and they definitely help us give us a better understanding on how the blockchain actually functions.
In this video, BlockchainWTF’s Jeremy Cogan explains how to read a transaction’s receipt on a blockchain explorer. He’ll cover the different capabilities of a blockchain explorer, how to read a receipt, and any associates fees that come with these transactions.
Today we’ll be showing you with Etherscan.io.
Now lately I’ve conducted some transactions in ether. I’m also familiar with their blockchain explorer, Etherscan. On Etherscan, you can search by:
- transaction hash (Txhash),
- token, or
- Ethereum Name Service (ENS) address.
It will come up with all information associated with the address or the transaction, making it a very handy tool!
What is a block explorer?
It’s important to note that this is the block explorer for Ethereum. However, each cryptocurrency has a block explorer. All you have to really do to find the block explorer for your blockchain? Simply type in the name of the blockchain in Google followed by block explorer — for example, dash block explorer –, and it should be one of the first few results.
All these sites really function the same way. They just give details and insight into each transaction, like what each new address has been doing. It helps you navigate the information around the blockchain.
The blockchain identifies each transaction with something called the transaction hash, or tx. This is a long alphanumeric string of characters that is unique to every single transaction on the blockchain, so it can be used to identify specific transactions. This tx is used to encrypt these transactions data.
Here you can see a couple. These are the hash numbers of transaction numbers. You can also search up in the bar by transaction hash, and they’ll pull up the exact details of that transaction.
Reading a transaction receipt
You can see a bunch of recent transactions that have recently occurred. I’m clicking on random one, and that will pull all of the details for that specific transaction. In the image below, you can see the transaction hash that we just talked about in red — the unique identifiers used to identify every transaction on the blockchain. You can save that hash for your records for every transaction, and have a reference to bring that up by just searching by that transaction hash. All those details will be at your fingertips.
This next bit of information also acts as an identifier. In the image, you can see you have the block height in blue, which is the number of the block that your transaction is contained in. Now you may recall that each block is made up of several different transactions hashes and all the information that goes along with that transaction identifies a specific transaction. While the block height identifies which block or where that transaction is contained in.
These next bits of information are pretty self-explanatory. You see time stamp in black, which is simply when the transaction occurred. Also, the address that is sending the funds to the address that’s receiving the funds in green, and the value of the cryptocurrency that’s being sent in purple, which you can see in ether and in USD.
Remember we’re working with ether — that’s why we’re on Etherscan. That’s partly why you can see an approximate monetary value in USD of how much the transaction was worth.
Here’s where things get a little bit more complex when it comes to reading receipts. These last couple items at the bottom, we’ve yet to go over, all have to do with the gas. So let’s give you a reminder and what exactly gas is and what it does so we actually know what we’re reading here. Gas is the unit that is consumed by the Ethereum Virtual Machine (EVM), which processes transactions. It is a separate unit from ether, but the monetary cost is paid for in ether. Gas is essentially a transaction fee.
But here’s the good part! The transaction fees literally usually come to cents! You can see the actual transaction fee for this transaction — and they sent about 115 US dollars — was only 10 cents in gas. 10 cents to send that amount of money it’s pretty impressive! You can see that in black in the image below.
Anyway in red you have a gas limit which is just basically the amount of gas that you’re willing to spend on a transaction. You might not hit that limit. As you can see, the gas limit was 50000, but the gas used by the transaction was just under 21000. So pretty much any ether that they put up for gas that’s different will be refunded to the sender. You can see those items in the receipt in red.
In blue is the standard gas price, which is exactly how much does the gas cost. Its gas price is simply the fixed price that gas is set up at. There you can see the exact amount of ether. Again it’s a very small number, and you have something called GWEI (pronouned *gwee*). GWEI is a denomination of ether. So instead of writing this big number, it can be simplified to the 25 GWEI.
The last thing I want to go over on a receipt is this nonce. What exactly is a nonce? A nonce is used to prevent something called double spending. Basically it’s a number the acts as an identifier, so it doesn’t allow you to spend the same cryptocurrency twice in two separate transactions. The nonce number that prevents that double spending is shown to the right.
Another example with an ERC-20 Token
So now that we went over that last receipt, I want to look at one that’s a little bit different! This one has pretty much all the same details: transaction hash, block height, timestamp, etc.
The only thing that’s different is the two columns. This is because this transaction was not sending ether from one place to another. Instead, this was actually an investment in the KIN token ICO. You can see that the person laid down 75 ether. At the time of the transaction, that was worth about 20.5 thousand.
Instead of sending it to a normal a third party address, they sent it to the KIN contract. Since KIN is an ERC-20 token, it can function this way. So this person’s address sent 75 ether and got the equivalent amount in the KIN token.