Every single transaction on the blockchain is assigned a unique transaction ID, also known as a transaction hash. Often, the terms can be found with the abbreviations tx or txn substituted for transaction.
Explaining the cryptography behind this number in full would require a few more articles. However, for our purposes, it will do to simply understand this hash number as a condensed form of the transaction's data -- in other words, details such as the addresses involved, the timestamp, and the quantity of tokens exchanged.
Locating the transaction ID is straightforward, and varies depending on the platform you're using to access MetaMask. Scroll down for a how-to relating to MetaMask Mobile, our smartphone app.
MetaMask browser extension
As soon as you submit a transaction to the network, it will appear in the Activity tab of your account, detailing whether you were sending or receiving.
Simply click on the transaction in question:
This should display the interface below, at which point you will notice the convenient Copy Transaction ID option. This will copy the ID to your clipboard, ready for however it's needed.
Alternatively, and if you want to see more detail, you could also select View on block explorer, which will take you to the Etherscan page for your transaction. Here, the transaction ID is referred to as the transaction hash.
To access the transaction ID in mobile, first we need to be able to view the transactions. There are two ways to do this depending on how you want to narrow them down:
Option 1: View transactions by token type
Accessible from the wallet homepage, which displays all the token types which have previously been added or held by the wallet, this method is useful if you want to distinguish tokens.
From here, tap the relevant token type to bring up its transactions, and select the one you're looking for:
Option 2: Transaction history
Another way of reaching this stage is to go via the hamburger icon in the top-left to Transaction history, which will be more suitable if you want to review all transactions associated with the address.
After finding the transaction you want to investigate, tap it to bring up its details.
Whichever method you used, you'll be presented with basic information and the transaction status. At the bottom you'll see an option to view on Etherscan -- select this to open Etherscan within the app's native browser. You'll then be able to easily locate the transaction ID listed as 'transaction hash' on Etherscan.