Networks
Networks are different Ethereum environments you can access for development, testing, or production use cases. Since Ethereum is a protocol, there can be multiple independent "networks" that conform to the protocol without interacting with each other.
Your Ethereum account will work across the different networks, but your account balance and transaction history won't carry over from the main Ethereum network. For testing purposes, it's useful to know which networks are available and how to get testnet ETH to play around with. In general, for security considerations, it's not recommended to reuse mainnet accounts on testnets or vice versa.
Prerequisites
You should understand the basics of Ethereum before reading up on the different networks, as the test networks will give you a cheap, safe version of Ethereum to play around with.
Public networks
Public networks are accessible to anyone in the world with an internet connection. Anyone can read or create transactions on a public blockchain and validate the transactions being executed. The consensus among peers decides on the inclusion of transactions and the state of the network.
Ethereum Mainnet
Mainnet is the primary public Ethereum production blockchain, where actual-value transactions occur on the distributed ledger.
When people and exchanges discuss ETH prices, they're talking about Mainnet ETH.
Ethereum Testnets
In addition to Mainnet, there are public testnets. These are networks used by protocol developers or smart contract developers to test both protocol upgrades as well as potential smart contracts in a production-like environment before deployment to Mainnet. Think of this as an analog to production versus staging servers.
You should test any contract code you write on a testnet before deploying to Mainnet. Among dapps that integrate with existing smart contracts, most projects have copies deployed to testnets.
Most testnets started by using a permissioned proof-of-authority consensus mechanism. This means a small number of nodes are chosen to validate transactions and create new blocks – staking their identity in the process. Alternatively, some testnets feature an open proof-of-stake consensus mechanism where everyone can test running a validator, just like Ethereum Mainnet.
ETH on testnets has no real value; therefore, there are no markets for testnet ETH. Since you need ETH to actually interact with Ethereum, most people get testnet ETH from faucets. Most faucets are webapps where you can input an address which you request ETH to be sent to.
Which Testnet should I use?
The two public testnets that client developers are currently maintaining are Sepolia and Goerli. Sepolia is a network for contract and application developers to test their applications. The Goerli network lets protocol developers test network upgrades, and lets stakers test running validators.
Sepolia
Sepolia is the recommended default testnet for application development. The Sepolia network uses a permissioned validator set. It's fairly new, meaning its state and history are both quite small. This means the network is quick to sync to and that running a node on it requires less storage. This is useful for users who want to quickly spin up a node and interact with the network directly.
- Closed validator set, controlled by client & testing teams
- New testnet, less applications deployed than other testnets
- Fast to sync and running a node requires minimal disk space
Resources
- Website(opens in a new tab)
- GitHub(opens in a new tab)
- Otterscan(opens in a new tab)
- Etherscan(opens in a new tab)