Understanding Ethereum Testnets and Wallet Security Basics

MetaMask empowers users to securely manage wallets and conduct transactions on Ethereum testnets like Sepolia.

### Introduction to Ethereum Testnets and MetaMask Wallet Setup
* 🔗 In this tutorial, we explore the Ethereum Sepolia testnet, where transactions can be **simulated without using real money**.
* 🧑 The transaction details include the sender and receiver's addresses, the value of the transaction (**0.1 ETH**), and its fiat equivalent, which is **zero in testnets**.
* 🌐 Testnets like Sepolia are essential for developers to **practice transactions**, as they are often **subject to change** and can be **discontinued by users**.
* 🔒 Setting up a MetaMask wallet is crucial for interacting with these testnets, and users must **securely store their secret recovery phrase**, which acts as the **master key to their wallet**.
* 💻 Users are encouraged to create a dedicated wallet for testing purposes, ensuring that **real funds are never used** during the course.
* 💸 To obtain testnet ETH, users can access faucets, such as **faucets.chain.link**, which provide **free testnet Ethereum** for transactions.
* 📈 Understanding transaction hashes and block confirmations is vital for navigating the blockchain ecosystem, as these identifiers are **unique to each transaction**.
* 🛡 The emphasis on wallet security highlights the importance of **safeguarding one's secret recovery phrase** to prevent **unauthorized access to funds**.

this is the Ethereum website, ethereum.org. We are going to make a transaction on a test Ethereum blockchain. I'll explain what that means in a little bit. This is going to be our first-ever transaction that's made on the blockchain, and this process of making a transaction is going to work the exact same across all EVM-compatible blockchains and layer twos like Arbitrum, Ethereum, ZK Sync, and etc. I'll explain what EVM means in the future. For now, just follow along and have fun running your first transaction. Now, in order for us to send a transaction on any of these EVM chains, the first thing that we need to do is set up a wallet. So, I'm going to go to MetaMask because it's one of the most popular wallets and one of the easiest wallets to use. I'm using the Brave browser, but it works for Chrome or Firefox or really any other popular browsers out there, and it's just going to be an extension in the top right hand of our browser. It's going to make it

very easy to see anything to do with our wallets and our transactions very easily, and it's going to store all of our EVM-based currencies and EVM-based transactions. So, I'm going to go ahead and hit Add to Brave ADD extension, although Brave does also come jam-packed with its own wallet. So now we come to the Get Started page, and I'm going to go ahead and select Create a New Wallet. Sure, we'll agree to help out MetaMask. Now we're going to create our password. Make sure it's really secure. For the purpose of this demo, mine's going to be kind of mediocre. Now, I'm going to preface this. This wallet that you're making right now as you follow along with me, this is going to be your development wallet. So, if you want to make the password a little bit weak just so that you can test things out very quickly, go for it. Just know we're never ever going to put real money into this wallet. It's good if you treat this as if it is a real wallet. That way, you'll get

used to, and you'll get familiar with good wallet safety. You will then get a video like this, which will teach you about the secret recovery phrase, which we saw a little bit earlier when we were creating our wallet. Let's watch this video. Betamask is a new way to connect to sites and applications. On traditional websites, a central database or bank is responsible for controlling and recovering your accounts. But on metamask, all of the power belongs to the holder of a master key. Whoever holds the key controls the accounts. Your secret recovery phrase is your master key. It's a series of 12 words that are generated when you first set up metamask, which allow you to recover your wallet and funds if you ever lose access. It's important that you secure your wallet by keeping your secret recovery phrase very safe and very secret. If anyone gets access to it, they will have the master key to your wallet and can freely access and take all of your funds. To secure your metamask wallet, you'll want to safely save your secret recovery phrase.

you can write it down, hide it somewhere, put it in a safe deposit box, or use a secure password manager. Some users even engrave their phrase onto a metal plate. Nobody, not even the team at Metamask, can help you recover your wallet if you lose your secret recovery phrase. If you haven't written down your secret recovery phrase and stored it somewhere safe, do it now. We'll wait. And remember, never share your secret recovery phrase with anyone, not even us. If anyone ever asks you for it, they're trying to scam you. That's it. Now you know what a secret recovery phrase is and how to keep your wallet safe and secure. Awesome. So, that was a great introduction to keeping your wallet safe. We'll talk a little bit more about safety with our wallets in the future. Let's go ahead and select secure my wallet now. This is where we need to write down our secret recovery phrase and save it in a very secure place. It gives us some tips here, like a password manager, a safety deposit box, or split it.

up and keep it in multiple secret places. For the purposes of this video, I'm going to be showing you the secret recovery phrase because I'm not going to put any real money into this, but you should never, ever do this. Additionally, you'll sometimes hear mnemonic as a synonym for secret recovery phrase. The main takeaway from all this is you should never share any of this. This is for you only. If you show this secret phrase to anybody else, they will have access to not just one account but every account that you make in Metamask. So, be absolutely certain to not share this with anybody. So again, I know I'm belaboring the point a little bit, but everything that we're going to do in this tutorial, we're going to do with fake money and fake assets, and never put actual money into this account that we're making here. Once you get familiar with using Metamask and working with the tools and staying secure, then you can go ahead and create a separate Metamask that will have real funds in it if you want to put real money in.

different metamask. A lot of browsers have a profile option, and maybe you can make a new profile, install metamask on that different profile, call that profile real money profile or something, and that's where you will store your money. But for this video, for this tutorial, the metamask that you are using is going to be specifically for testing things out, and you will never store real money to it. I'm going to harp on that a lot more in this course, so even if you're coming here and you have a wallet, I highly recommend still making a brand new one for this tutorial just in case you don't actually code something or do something autonomous and give away your funds. If this is your first wallet, then great, but again, when you're working with real money, if you lose access to the secret phrase, you will lose access to all your money. So be sure to write this down. Promise me that you won't use real money for this course. Great. I'm going to hit copy to clipboard for now, and we're going to go ahead and hit next. Now we

need to confirm by adding our seed phrase back in. We can go ahead and hit confirm, and we now have created our wallet. Let's go ahead and collect. Got it. Awesome. Now we can see the interface of our Metamask full screen, and depending on your browser, what you can normally do is set this little puzzle piece on your browser and select this pin button. So now we can pin our Metamask into the top of our browser, and we can click it like so, and we can see it gave a little drop-down like this, and we could see the same information in this little drop-down as there is on the full screen. Now, even if you lose access to that page, now that this is bookmarked in your browser, you can select your Metamask, select these three dots, and hit expand view to reach this tab. Now, additionally, what we can do in here is we can actually go up to our accounts, and we can actually create multiple accounts by hitting create account. And if you wanted to, you could give it a name here. I'm just going

to leave it as default for account two, and now we have two separate accounts. We have an account zero with an address and an account two with an address as well. Both of these accounts actually share that same secret phrase, so anybody with access to the secret phrase can actually have access to both accounts. However, they have different private keys, and that's what makes them different. We'll talk a little bit more about that in the future. If somebody gets access to a private key, they'll get access to a single account. If they get access to the secret phrase, they'll get access to all the accounts that you make, even if you made a third one. They'd get access to this one as well. Now, if you look up in the top right of the screen here, you'll see the section that says Ethereum mainnet. This is our networks tab, and if you click it, you can see all the different networks that our MetaMask has access to. Ethereum mainnet is the main network of Ethereum, and this is where real money is spent and used for

this course, we're not going to be working with the Ethereum mainnet. We're instead going to be working with something called a testnet. For both engineers and non-engineers, we often need a place to test or simulate our transactions. And for the developers here throughout this course, we are going to teach you another technique for testing out your transactions on a local network. And a local network is actually going to be the preferred way we do our testing and our simulations. However, it's still really important to see and to understand what a real transaction looks like, and that's what a testnet will do for us. It simulates exactly what a mainnet or a live money network would look like. However, there's no real money at stake, and we don't actually have to spend any money. To see some of the testnets that come default with MetaMask, we can hit the show/hide button, which will bring us to the settings page of MetaMask. We can turn on show test networks, and if we scroll back up now if

we hit our networks tab. Actually, let's go ahead and close out of settings. Now, if we hit this drop-down, we can see Gorelli test Network, Sepolia test Network, and Linea Gorelli test Network. These networks are test networks that resemble Ethereum or Polygon or Linea or Arbitrum or Optimism or ZK Sync or any other EVM-compatible chain that we want to work with. And again, we'll define EVM in the future. And then we can actually switch the network that we're working on simply by clicking another network. So, let's switch to Sepolia. We can see our network has changed up here, and now we can see we have zero support. So, on ETH mainnet, this new account has zero Ethereum, and on the Sepolia test Network, we also have zero Sepolia ETH, which makes sense because this is a brand new wallet, and we haven't put any money into this brand new account yet. So, of course, we have zero at the time of recording. Sepolia is one of the most popular test networks out there, so we're

going to be working mainly with Sepolia throughout this course. However, testnets often change because, again, they're run out of the goodness of people's hearts, and sometimes people stop running them. You should absolutely have either the web3dev data education site up or the GitHub repository associated with this course. An important note: sometimes you'll see this as the Chain Excel org Foundry flow course. We recently renamed it to the Siphon Foundry folk course, so this is the correct link, but if you see Chain Excel org, that's fine as well. You should scroll down to the recommended testnets section to make sure you're on the most up-to-date testnet at the time of recording. Like I said, we're working with Sepolia throughout this course. We are going to show you how to work with different testnets and different networks as well because it's incredibly important to do so. The blockchain world is moving into a multi-chain world, and especially with the popularity of L2s, which help Ethereum scale, learning the differences

between different chains and different L2s is incredibly important now. Same as Ethereum. What we can do is we can actually go to Simpolia Etherscan. So we'll go to sympolia.etherscan.io, and we can grab our address from Metamask by clicking and copying the address here, pasting it into the Sapolia Explorer. And same as Ethereum, we can see our account balance. We have zero ETH. There are no transactions, no token transfers, nothing because obviously it's a brand new wallet. Now, I'm showing you this because pretty soon we're going to send our first-ever blockchain transaction. If you've never sent a blockchain transaction before, we're going to do it on this testnet to give you some confidence as to what a transaction actually looks like when you do move over to a mainnet. And I'm showing you this site now because you're going to see when we send a transaction, a lot of this information is going to get updated. Now, just remember, like I said earlier, a testnet is run under the goodness of

people's hearts, so please use the transactions sparingly. Once you send your first transaction here, try not to send too many more, as one is good enough for you to see what's going on anyways. And in order for us to simulate one of these transactions, we're going to go to a faucet, right? Testnet testnets have this thing called faucets, which allow us to get some free Sapolia ETH so that we can test out sending transactions and receiving transactions. If you go to the GitHub associated with this course or web3dev.education, we can scroll down to this testnet faucets section and select one of the links to go to one of these testnet faucets right now. The recommended faucet that we're working with is faucets.chain.link. But be sure to use the GitHub repo or web3dev.education to be most up-to-date. What this is going to do is we're going to ask this faucet site to send us testnet Ethereum, and this is why this testnet Ethereum isn't

worth any real money since we can get it for free anytime that we want. These obviously don't exist on mainnet. You can't get free mainnet Ethereum via a faucet. Now, what we can do is we can actually connect our wallet to this site, and we can get some free test net Sepolia ETH. This will make it so that in our balance here, we'll actually have some Sepolia ETH to play with. So, to do this, what we're going to do is we're going to go ahead and hit connect wallet, accept the Chainlink terms of service. I've already read them. Our MetaMask is going to pop up to connect it to this website. Now, get familiar with this interface because this is how websites will interact with our wallet and interact with the blockchain. Connecting our account to the site, we'll first select the specific account that we want to connect. We're just going to choose account one. We'll hit next, and then we'll go ahead and hit connect. And now we can see our wallet address in the top

right, and we can see that we're connected on the Ethereum Sepolia testnet. If we go up to our wallet and we actually switch to Ethereum mainnet, you can see that the website has actually changed this little drop-down to Ethereum mainnet. And if we go in here, we can actually switch to Ethereum Sepolia, and our MetaMask will pop up with this switch network button, which will help us switch the network for us. So now we're back on Sepolia test network. Connecting to these websites is how we give these websites a way to interact and connect with our wallets. We can go ahead and select this, hit these three dots, and hit disconnect this account. But don't worry, anytime we want to send a transaction, the website has to ask us if we want to send a transaction. So just by connecting to the site, it won't actually send a bunch of transactions for us. And if we scroll down, we can see our wallet address is placed right here, and we can see we can request test link, and we can also

request test eth. For now, we don't need any test link, so we're going to leave that off. But in the future, we will come back to the site to get some test link. For now, we're just going to get 0.1 test Ethereum, and if all goes well, we should hopefully see it in our Simplelia Ether. In order for us to get this test Ethereum, we do have to log in via Twitter. If you don't have a Twitter, you can use any of the other faucets in the test nets faucets area of the GitHub, such as the Alchemy Sepolia faucet or the Simplelia proof of work faucet. But if you are on Twitter, now is a great time to give me a follow, maybe give me a shout-out, and maybe say, Hey, sending my first transaction. Thanks, Patrick Alpha C, or not, whatever you want to do, just some light chilling of my own Twitter account. Anyways, we can log on via Twitter, we can authorize this app, verify with that we're human, give our AI overlords the prompt here, Oh, make sure

We don't select the link, and let's go ahead and send the request now. What's going to happen is it's going to give us this transaction hash on Sepolia, and after a delay, we'll see it go from initiating to waiting for a confirmation to token transferred, and we'll see a transaction hash. And if we click the transaction hash, we'll see a transaction that was sent to our address. So, this will be the first transaction that we get to see, and there's a ton of information here, but the most important piece is if we open up our MetaMask now, we can see we now have 0.1 Sepolia ETH in our account. And if we copy the address again, we paste it into here, we can see now we have a 0.1 ETH balance. You might have to wait several minutes for the transaction to finish going through, and if you accidentally refresh your browser again, we can go ahead and just select our MetaMask, copy our address, and paste it into Etherscan or just view it right in our MetaMask here.

and if you missed that piece about the transaction data, if we go back to etherscan with our address, remember we're on sepolia etherscan, and we scroll down, we can see this most recent transaction hash that just occurred, and we can click the link here, and we can see that detail about the transaction again here. Now importantly, remember though, this is on sepolia. If we switch back to mainnet Ethereum, you'll see we have zero ETH on mainnet Ethereum. If we switch to Goerli test network, you'll see we have zero Goerlis on that network. If we switch to Linea Goerli ETH or any other network other than sepolia, you'll see that sepolia is the only one that has the 0.1 sepolia ETH. If you want to practice working with a different test net, feel free to scroll up back to the faucet, select a different test net, and try to get tested in one of these different test nets. Just be sure to take a look at what test nets your MetaMask

comes with since some of the networks. This faucet is compatible with. Don't come built into our meta mask. But again, like I said in the future. I'll teach you how to add these different networks to our metamask in the future. But huge congratulations. You received your first transaction. Because again, this faucet is US asking them to send us money. It's not us sending money. It's them sending money to us. And if this is the first transaction that you've ever sent. You should be proud of yourself already. Give yourself a big pat on the back. And here's a picture of me holding a cat. With that cat's face all over my pajamas. As a congratulations. Now once more. Let's grab our address. Paste it into etherscan here. And scroll down. And we're going to learn a little bit more about what actually went down. What actually happened in this transaction. You can see on etherscan. It gives us some basic details. It says from and to. From is going to be another address. A different address. An address controlled

by the faucet, and two is obviously going to be our address. And if we select this transaction hash, we can see even more details in here. Understanding all these different fields is essential to becoming a smart contract developer and even just a web 3 or Ethereum or blockchain user. So let's learn a bit of the basics of what's actually going down in this transaction. The first field on this page is the transaction hash. You can even see a little question mark here, which tells you a little bit more about it. It's a unique identifier for this specific transaction on this network. So this specific transaction hash, we can even copy and paste this into the address bar, and we'll get the exact same transaction back. This is the only transaction in the entire blockchain that will have this transaction hash. It's the unique identifier. It identifies the transaction of sending 0.1 ETH from the faucet address to our address. We can see the status of this was successful. We can see the block number and the number of block confirmations, which we will explain in

the future we can see the time step, which of course is when this transaction occurred. We could see the from and to, who initialized the transaction, and who it was sent to. If we select this from and open this in a new tab, we can see some details about who actually sent us this test eth. And if we go back to the transaction detail and keep going, we can see the value here, which again, if we roll over, it's the value of ether or testnet ether, and then in parentheses, the Fiat value or the dollar value, which of course, since this is a test net, it's always going to be zero. The value of this transaction was 0.1 eth.

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Getting Free Sepolia ETH and Wallet Security

You can obtain free Sepolia ETH by connecting your wallet to a specific site, as testnets offer free cryptocurrency unlike the mainnet.

The transaction hash is a unique identifier for each transaction, and it's important to understand the details of these transactions for blockchain development.

It's crucial to securely store your secret recovery phrase, as losing it can result in permanent loss of access to your wallet, and you should never share it with anyone.

Connecting to Ethereum Testnets with MetaMask

MetaMask allows users to switch between Ethereum mainnet and Sepolia testnet, facilitating wallet interaction with websites.

Testnet faucets provide free Sepolia ETH for testing transactions, and it's recommended to use a separate profile for MetaMask to avoid storing real money.

The course will focus on using testnets for transaction simulations, with an emphasis on not using real money during the tutorial.

Setting Up a MetaMask Wallet and Receiving Sepolia ETH

The process begins with sending a request, which generates a transaction hash on Sepolia and eventually transfers 0.

The user can track the transaction through MetaMask and Etherscan, and the wallet setup includes creating a new wallet and a secure password.

It's emphasized that the wallet is for development purposes only, and the secret recovery phrase should never be shared to maintain account security.

Managing Accounts and Networks in MetaMask

MetaMask allows users to create multiple accounts with a shared secret phrase but different private keys.

The Sepolia test network is the only one with a balance of 0.

1 Sepolia ETH, while other networks show zero balance.

Users can pin MetaMask to their browser, bookmark it, and easily switch between accounts and networks.

Getting Started with MetaMask and Test Networks

MetaMask does not have built-in network support, but the speaker plans to teach how to add networks in the future.

The first transaction received from a faucet is a significant milestone, and the speaker encourages celebrating this achievement.

Test networks like Sepolia and Gorelli are available for use, and the speaker guides on requesting test Ethereum and logging in via Twitter for verification.

Setting Up and Understanding Ethereum Transactions

Ethereum transactions can be tracked by time, sender, and receiver, with testnet transactions having a zero dollar value.

The course will primarily focus on the Sepolia testnet, with a goal to work with different testnets and networks.

Setting up a MetaMask wallet is essential for sending transactions on EVM-compatible blockchains, and securing the secret recovery phrase is crucial for wallet safety.