Ganache

 Fake simulated local blockchain.

Cardano - public blockchain

Founded by Charles Hoskinson (Ethereum cofounder) in 2015.

Proof of stake

Internal cryptocurrency: ADA.

Keyword: Contract

 Similar to class in Java and other object oriented programming languages.

Specify version in each .sol file

 pragma solidity >=0.6.0 <0.9.0;

or

pragma solidity 0.6.0;

or

pragma solidity ^0.6.0

.sol file

Remix IDE

 Work with solidity, work with smart contracts, and deploy to blockchains.

Sidechain Vs Rollup

 A sidechain, although also a layer-2, is different from a rollup in that a sidechain derives its security from its own protocols, whereas a rollup derives its security from the base layer.

Layer 1 Vs Layer 2

Layer 1 examples:

Ethereum, Bitcoin, Avalanche

Layer 2 examples:

Chainlink, Arbitron (a rollup that seeks to solve the scalability issue), Optimism (also a rollup that seeks to solve the scalability issue)

Current proof of stake chains

avalanche

solano

polygon 

polkadot

terra

Longest chain rule

Two types of blockchain attacks

1.  Sybil attack

2.  51% attack

Bitcoin halving

The Bitcoin block reward being cut in half.

This is supposed to happen roughly every 4 years.

Transaction fee VS block reward

 The node that solves the blockchain riddle first gets rewarded with these two portions.

The transaction fee is paid by the party executing the transaction.

The block reward comes from the blockchain itself.

Miners Vs Validators

Miners - proof of work network

Validators - proof of stake network

In proof of stake, there is also a gas fee, but it is paid to validators instead of miners.

Block time

 How long it takes between blocks being published on a blockchain.

Consensus

Consensus:

proof of work

proof of stake

Consensus is the mechanism used to agree on the state of a blockchain

1. Chain selection

2. Sybil resistance -> proof of work

Source:

Patrick Collins

https://www.youtube.com/watch?v=M576WGiDBdQ&t=191s

ethgasstation.info

 A site that estimates the gas for a transaction.

Units converter - Ethereum

See how much a certain amount is in Wei , Gwei, and Ether units.

eth-converter.com

Gas

Gas: awarded to node operators for successfully including a transaction on a blockchain (adding a transaction to a blockchain).

The amount of gas a certain transaction requires depends on how "computationally intensive" that transaction is, for example, sending crypto to one address would require less gas than sending crypto to 100 addresses.

Gas: measure of computation use

Gas price: how much it costs per unit of gas

gas limit: maximum amount of gas for a transaction

transaction fee: (gas used) x (gas price)

for example:

16,000 gas @ 1 GWEI per gas = 16,000 GWEI

Gas prices fluctuate based on demand on the blockchain.

Source:

Patrick Collins

https://www.youtube.com/watch?v=M576WGiDBdQ&t=191s

Etherscan - a block explorer

 A "block explorer" is an application that allows us to view transactions on a blockchain.

Etherscan is an example of a block explorer.

Faucet - Rinkeby

 faucet.rinkeby.io

A faucet is an application that gives free tests tokens for testing use.

Test networks:

Rinkeby

Ropstem

Kovan

Goerli

Website: Eth Gas Station

 ethgasstation.info

This website estimates gas fees.

Etherscan

Etherscan can be used to see what's going on with a crypto wallet. Just enter the address of the wallet into Etherscan.

DAO - decentralized autonomous organization

Oracles

Smart contracts are often paired with oracles to interact with the real world or the outside world. These types of smart contracts are called hybrid smart contracts.

An oracle network can allow smart contracts to obtain real-world data, or perform external computations, etc.

Smart contracts - self-executing code in blockchain

Smart contracts are a set of instructions that when placed on a blockchain, are a self-executing piece of code. This allows for trustless agreements to be formed.

Blockchains are transparent.

 Everyone can see everything that happens on a blockchain.

Trustless

 Trustless = you don't need to trust any party.

Smart contracts, blockchain, and decentralized apps allow our transactions to be trustless.

Immutibility

 Immutable = cannot be changed

What is a crypto wallet and how does it work?

 A crypto wallet is actually a piece of software that:

(1) Stores our private keys and public keys.

(2) Can interact with the blockchain.

(3) Can send and receive crypto.

[Note: the features listed above are common features found in many crypto wallets, but whether or not a particular wallet supports all of the above features depends on the wallet software. Different wallets may have different features.]

It is important to know that our crypto is not actually stored in our wallets. Our crypto lives in the blockchain, and wallets are software that makes it easier for us to access and manage our crypto.