and synchronized across multiple sites, institutions, or geographies, accessible by multiple people. It allows transactions to have public "witnesses." The participant at each node of the network can access the recordings shared across that network and can own an identical copy of it. 7 https://www.investopedia.com/
and confirm new transactions to the blockchain (miners are getting paid for their work) • to prevent double-spending by bad actors (it is extremely expensive to"hack" the network) It is also the way that new bitcoins are introduced into the system. https://supchina.com/ 8
state) that resides at a specific address on the Ethereum blockchain. Smart contracts are programs stored on a blockchain that run when predetermined conditions are met. A smart contract is an agreement between two people in the form of computer code. The transactions are processed automatically without a third party. A smart contract is a self-executing contract with the terms of the agreement between buyer and seller being directly written into lines of code. Smart contract definitions 10
amount in first currency, • preferable exchange rate, • gas. Alice sends • amount in second currency, • preferable exchange rate, • gas. The smart contract program computes the exchange rate, the volume and sends the resulting amounts to Bob and Alice. 11 $$ ££ $$ ££
other participants send: • money to play on, • seed number for the algorithm • gas for the contract. The smart contract computes the winner using provably fair random number generator. The winner receives all the money from the contract. Carol 12 $$ $$ $$ $$
to invest, • asset specification, • gas for the contract. The smart contract finds and purchases an asset. Then, after the specified period, sells it and sends the money back to Alice 14 $$ $$$
and other participants send: • preferable investment spec, • money to invest, • gas for the contract. The smart contract computes the collective decision, invests the money, and sends back the dividends. Carol … 15 $$ $$ $$ $$$
selling tokens • ICOs are unregulated, so investors must have a lot of caution and diligence • ICOs are similar to initial public offerings (IPO), but coins issued in an ICO can also have utility for a software service or product Initial Coin Offering (ICO) https://ambisafe.com/ 17
to any other token; no tokens have special rights or behavior associated with them. ERC20 tokens are useful for • digital currency, • voting rights, • staking etc. https://www.brookings.edu/ 21
or physical assets: • Physical property — houses, unique artwork • Virtual collectables — unique pictures of kittens, collectable cards • “Negative value” assets — loans, burdens and other responsibilities All houses are distinct and no two kittens are alike, and a loan usually has numerous details to make it unique. NFTs are distinguishable and you must track the ownership of each one separately. https://www.besttemplates.com/ 23
backbone of a DAO is its smart contract The contract defines the rules of the organization and holds the group's treasury Decisions are governed by proposals and voting Votes counted, and outcome implemented automatically without trusted intermediary DAO implementation https://riskgroupllc.com/ 26
from anyone in the world and the group can decide how they want to spend donations. • A freelancer network – you could create a network of contractors who pool their funds for office spaces. • Ventures and grants – you could create a venture fund that pools investment capital and votes on the investments. DAO examples https://cointelegraph.com 27
to govern the behaviour of accounts within the Ethereum state Solidity is a curly-bracket language influenced by C++, Python and JavaScript Solidity is statically typed, supports inheritance, libraries and complex user-defined types among other features 30
Everyone can read entries in the database just by participating in the network. If you want to change something in the database, you have to create a transaction which has to be accepted by all others. A transaction is a message that is sent from one account to another account. It can include binary data (which is called “payload”) and Ether. 33
database in a consistent state. Example: Money transfer transaction account1.balance = account1.balance - sum account2.balance = account2.balance + sum A transactional system would make both entries pass or both entries would fail. 34
address space: • External accounts that are controlled by public-private key pairs (i.e. humans) • Contract accounts which are controlled by the code (smart contracts). Every account has a balance in Ether, which can be modified by sending transactions that include Ether. The two types of accounts are treated equally by the Ethereum Virtual Machine (EVM). Ethereum accounts 35
EVM is completely isolated, which means that code running inside the EVM has no access to network, filesystem or other processes. Smart contracts have limited access to other smart contracts. The Ethereum Virtual Machine (EVM) 38
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