Notes

What is blockchain:
A blockchain is a digitally distributed, decentralized, public ledger that exists across a network.

What is smart contract:
They are a set of self-executing set of instructions without any third party intermediary. They get stored in the blockchain

The oracle problem:
Blockchains are a “walled garden” meaning that  whatever happens during a transaction happens in a box. But, if smart contracts want to be superior, they need to be able to communicate with the real world and outside of the block chain computation. 

What are oracle:
Oracles are devices that bring data into these blockchain or help compute data that the blockchain can interact with. 

Introducing chainlink:
Chain Link is a hybrid smart contract oracle network that allows you to bring external data into your smart contracts and also allow for other computations. 

Smart contract vs hybrid smart contracts:
Hybrid smart contracts have an off chain component to them - the real world data.

Etherscan:
It is a block explorer where you can see the detail of the transaction

Hash:
It is a unique fixed length string meant to identify a piece of data. They are created by placing said data into a hash function.
Hash algorithm: it is a function that computes a set of data into a hash. example: SHA256

Genesis block: first block in a blockchain

Mining a block:
Block - a list of transactions mined together.
Nonce - a “number used once” to find the “solution” to the blockchain problem.
Data
Previous - address of previous block’s hashHash - hash address of the current block.

Private key:
Your signature to transactions