Concepts

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• Consensus
• UTXO: Unspent Transaction Output

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• Double Spend Attack:
• Sybil Attack:
• 51% Attack:
• Fork Attack:

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• PoW: Proof of Work
• PoS: Proof of Stake

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methodologies

• P2PKH
  • multisig
  • P2SH

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SegWit: 隔离见证

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• public-key cryptography : One way to think of public-key cryptography is: a way for anyone to protect data such that only an authorized person can access it, and such that the authorized person can prove that he will have that access.
• ECC stands for elliptic-curve cryptography. One way to think of ECC is: a way to enable public-key cryptography that uses very small keys and very obscure math.

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Lightning is a layer-2 protocol that interacts with Bitcoin to allow users to exchange their bitcoins "off-chain". a way to transact bitcoins using off-chain channels between pairs of people, so that only a first and final state have to be written to the blockchain.

• What is a Layer-2 Protocol? A layer-2 Bitcoin protocol works on top of Bitcoin. In this case, Lightning works atop Bitcoin, interacting with it through smart contracts.
• What is a Lightning Channel? A Lightning Channel is a connection between two Lightning users.
• What is a Lightning Network? Putting together a number of Lightning Channels creates the Lightning Network.

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• Bitcoin wallet is the digital equivalent of a physical wallet on the Bitcoin network. It stores information on the amount of bitcoins you have and where it's located (addresses), as well as the ways you can use to spend it.
• Bitcoin address is literally where you receive money. Technically, it's a public key, though different address schemes adjust that in different ways, a Bitcoin address should be considered single use: use it to receive funds just once.
  • Legacy (P2PKH) address
  • SegWit address: 1. P2SH-SegWit (aka Nested SegWit) address, 2. Bech32 (aka Native SegWit, aka P2WPKH) address

the foundation of a Bitcoin address is a public key: someone sends funds to your public key, and then you use your private key to redeem it.

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digital signature is a combination of a message and a private key that can then be unlocked with a public key. Since there's a one-to-one correspendence between the elements of a keypair, unlocking with a public key proves that the signer controlled the corresponding private key.

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• faucets
• transaction is a bitcoin exchange. The owner of some bitcoins uses his private key to access those coins, then locks the transaction using the recipient's public key.
• What is a block? Transactions are transmitted across the network and gathered into blocks by miners. These blocks are secured with a mathematical proof-of-work, which proves that computing power has been expended as part of the block creation. It's that proof-of-work (multiplied over many blocks, each built atop the last) that ultimately keeps Bitcoin secure.
• What is block depth? After a block is built and confirmed, another block is built on top of it, and another ... Because this is a stochastic process, there's some chance for reversal when a block is still new. Thus, a block has to be buried several blocks deep in a chain before you can feel totally confident in your funds. Each of those blocks tends to be built in an average of 10 minutes ... so it usually takes about an hour for a confirmed transaction to receive six blocks deep, which is the measure for full confidence in Bitcoin.

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• What is a transaction fee? There's no such thing as a free lunch. Miners incorporate transactions into blocks because they're paid to do so. Not only do they get paid by the network for making the block, but they also get paid by transactors for including their transactions.

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• What is xpub? An extended public key. This is the combination of a public key and a chain code. It's a public key that a whole sequence of children public keys can be derived from.
• What is xprv? An extended private key. This is the combination of a private key and a chain code. It's a private key that a whole sequence of children private keys can be derived from.