Curiosity doesn’t kill the fox. It empowers it!
What is blockchain?
Blockchain is a type of distributed ledger technology, which according to Dan Tapscott, "is an incorruptible digital ledger of economic transactions that can be programmed to record not just financial transactions but virtually everything of value.”
Robin Chauhan, on their Medium, offers another interesting interpretation of blockchain:
“Blockchain is a record of transactions, spreading across the internet as more people use cryptocurrencies. Similarly, DNA is a record of genetic transactions and mutations that spread as life expanded across the earth. Both become more complicated over time as our DNA evolves and new blocks are added to the blockchain.
Each blockchain (Bitcoin, Ether, Ripple) is like a distinct species (human, chimpanzee, etc.). A blockchain can also be forked (like with Bitcoin Cash) to create a competing currency in the same way that two distinct species can share common ancestor.
In terms of transactions, they are organized into a series of blocks, which is the blockchain. A new block is created once verified. It means that a new pool of encrypted transactions (possibly including yours!) have been added to the blockchain.
In Proof of Work, miners (imagine gold miners) get rewarded for processing transactions.
What is Ethereum?
Ethereum is the blockchain, or decentralized platform, that runs smart contracts. It serves as “an enormously powerful shared global infrastructure that can move value around and represent the ownership of property.”
What are miners?
In Proof of Work, miners solve complex puzzles to process transactions with advanced computing devices. Miners/Verifiers/Validators in Ethereum are rewarded with Ether, the cryptocurrency of Ethereum, for processing transactions.
What is gas?
Gas is the unit of measure for how much computational work is required to process transactions and smart contracts in the Ethereum Virtual Machine. More complex smart contracts, and code, will require more gas to execute. (Just like how bigger and/or faster cars will require more gas to power them).
Gas limit is the maximum amount of gas you are willing to spend. In MetaMask, when you are sending ETH/transactions, you will be required to specify gas limit and gas price:
It specifies the amount of Ether you are willing to pay for each unit of gas.
MetaMask supports Ether(ETH) and Ethereum tokens such as ERC-20 and ERC-721 tokens. ERC-20 tokens are tokens created from the ERC20 standard. The ERC20 defines rules governing tokens to be accepted as ERC20 tokens, and leverage on the Ethereum blockchain to be transacted.
ERC-721 tokens are often referred to as "NFT's" aka Non-Fungible Tokens. You can think of these more as digital objects on the blockchain, such as pieces of art or collectibles, rather than a store of value such as a tokenized currency. Currently, only the MetaMask mobile app supports interacting with ERC-721 assets.
What is a block explorer such as etherscan.io?
A block explorer is an online blockchain browser. It displays the content of individual blocks, transactions, as well as the history and balance of addresses/wallets. Some popular Ethereum block explorers are etherscan.io, etherchain.org, ethplorer.io and etc.
Main Ethereum Network and Testnets
Transactions take place on the Main Ethereum Network. Testnets are created for developers to test smart contracts without paying gas. The testnets MetaMask supports are: Ropsten, Kovan, Rinkeby, and Goerli. You can use an "eth faucet" such as our own https://faucet.metamask.io/ , to request test ETH to interact with the testnet blockchains and practice sending transactions and funds to other testnet accounts. Please note, however, that the ETH in testnet are not "real" ETH and cannot be sent to mainnet addresses and exchanged for fiat value/other tokens.