ethereum blockchain

.....Ethereum..... is a distributed public block chain network that focuses on running programming code of any decentralized application.
it is a platform for sharing information across the globe that cannot be manipulated or changed.
Ethereum is a decentralized digital currency, also known as ETH.
Ethereum is a permissionless, non-hierarchical network of computers (nodes) which build and come to consensus on an ever-growing series of "blocks", or batches of transactions, known as the blockchain. Each block contains an identifier of the block that it must immediately follow in the chain if it is to be considered valid. Whenever a node adds a block to its chain, it executes the transactions therein in their order, thereby altering the ETH balances and other storage values of Ethereum accounts. These balances and values, collectively known as the state, are maintained on the node's computer separately from the blockchain, in a Merkle Patricia tree.

Each node communicates with a relatively small subset of the network, known as its peers. Whenever a node wishes to include a new transaction in the blockchain, it sends it to its peers, who then send it to their peers, and so on. In this way, it propagates throughout the network. Certain nodes, called miners, maintain a list of all of these new transactions and use them to create new blocks, which they then send to the rest of the network. Whenever a node receives a block, it checks the validity of the block and of all of the transactions therein and, if valid, adds it to its blockchain and executes all of said transactions. As the network is non-hierarchical, a node may receive competing blocks, which may form competing chains. The network comes to consensus on the blockchain by following the "longest chain rule", which states that the chain with the most blocks at any given time is the canonical chain. This rule achieves consensus because miners do not want to expend their computational work trying to add blocks to a chain that will be abandoned by the network.

Ether
Ether (ETH) is the cryptocurrency generated by the Ethereum protocol as a reward to miners in a proof of work system for adding blocks to the blockchain. It is the only currency accepted in the payment of transaction fees, which also go to miners. The terms "Ether" and "Ethereum" have become interchangeable in the cryptocurrency community. The block reward together with the transaction fees provide the incentive to miners to keep the blockchain growing (ie. to keep processing new transactions). Therefore, Ether is fundamental to the operation of the network. Each Ethereum account has an ETH balance and may send ETH to any other account. The smallest unit of ETH is known as a Wei and is equal to 10-18 ETH.

Ether is listed on exchanges under the ticker symbol ETH. The Greek uppercase Xi character (Ξ) is sometimes used for its currency symbol.

The shift to Ethereum 2.0 may reduce the issuance rate of Ether. There is currently no implemented hard cap on the total supply of Ether.

Accounts
There are two types of accounts on Ethereum: user accounts (also known as externally-owned accounts) and contracts. Both types have an ETH balance, may send ETH to any account, may call any public function of a contract or create a new contract, and are identified on the blockchain and in the state by their address.

User accounts are the only type which may create transactions. For a transaction to be valid, it must be signed using the account's private key, a 64-character hexadecimal string that should only be known to the account's owner. The signature algorithm used is ECDSA. Importantly, this algorithm has the property that it allows one to derive the signer's address from the signature without knowing the private key.

Contracts are the only type of account which has associated code (a set of functions and variable declarations) and contract storage (the values of the variables at any given time). Contracts are passive entities, only able to do anything as a result of an account calling one of its functions. During the execution of its code, a contract may: send ETH, alter its storage values, create temporary storage (memory) that dies at the end of the function, call any of its own functions, [Joanna ossinger]
What is Ethereum Gas?

TL;DR

Ethereum Gas is a unit that measures the amount of computational effort that it will take to execute certain operations.
Every single operation that takes part in Ethereum, be it a transaction or smart contract execution requires some amount of gas.
Miners get paid an amount in Ether which is equivalent to the total amount of gas it took them to execute a complete operation.
Ethereum Gas – is the lifeblood of the Ethereum ecosystem, there is no other way of putting that. Gas is a unit that measures the amount of computational effort that it will take to execute certain operations.

Every single operation that takes part in Ethereum, be it a simple transaction, or a smart contract, or even an ICO takes some amount of gas. Gas is what is used to calculate the amount of fees that need to be paid to the network in order to execute an operation.

In this guide, we are going to understand how gas works. But before we do so, there are several concepts that we must learn. So, without further ado, let’s begin our deep dive on Ethereum Gas.

What is Ethereum Gas: Step-By-Step Guide

Why is gas not needed in Bitcoin?

Bitcoin was created because everyone was

However, there was a problem with bitcoin which is a problem with all first-generation blockchains. They only allowed for monetary transactions, there was no way to add conditions to those transactions.

These conditions would need extremely complicated scripting. Something was required to make the process more seamless.

Smart contracts help you exchange money, property, shares, or anything of value in a transparent, conflict-free way while avoiding the services of a middleman.

Vitalik Buterin’s Ethereum is easily the stalwart of this generation. They showed the world how the blockchain can evolve from a simple payment mechanism to something far more meaningful and powerful.

Smart contracts are automated contracts. They are self-executing with specific instructions written in its code which get executed when certain conditions are made.

Smart contracts are how things get done in the Ethereum ecosystem. When someone wants to get a particular task done in Ethereum they initiate a smart contract with one or more people.

Smart contracts are a series of instructions, written using the programming language “solidity”, which works on the basis of the IFTTT logic .
[Ethereum is a distributed public block chain network that focuses on running programming code of any decentralized application.
it is a platform for sharing information across the globe that cannot be manipulated or changed.
Ethereum is a decentralized digital currency, also known as ETH.
Ethereum is a permissionless, non-hierarchical network of computers (nodes) which build and come to consensus on an ever-growing series of "blocks", or batches of transactions, known as the blockchain. Each block contains an identifier of the block that it must immediately follow in the chain if it is to be considered valid. Whenever a node adds a block to its chain, it executes the transactions therein in their order, thereby altering the ETH balances and other storage values of Ethereum accounts. These balances and values, collectively known as the state, are maintained on the node's computer separately from the blockchain, in a Merkle Patricia tree.