what is Genesis Block and why Genesis Block is needed?
The genesis block is the first block in any blockchain-based protocol. It is the basis on which additional blocks are added to form a chain of blocks, hence the term blockchain.
This block is sometimes referred to Block 0. Every block in a blockchain stores a reference to the previous block. In the case of Genesis Block, there is no previous block for reference.
In technical terms, it means that the Genesis Block has it’s “previous hash” value set to 0. This means that no data was processed before the Genesis Block. All other blocks will have sequential numbers starting by 1, and will have a “previous hash” set to the hash of the previous block.
The hash of genesis block is added to all new transactions in a new block. This combination is used to create its unique hash. This process is repeated until all the new blocks are added to a blockchain.
The number used to refer to the ordering of blocks is known as the block height number. It starts at 0 with the Genesis Block.
Bitcoin genesis block
The most famous Genesis block was “Bitcoin Chain”, which was created by Satoshi Nakamoto on January 3rd. This block has a 50-bitcoin reward that is unavailable forever. It is unclear, whether the Genesis Block reward was mined or not, and Satoshi Nakamoto has made no comment.
A “coinbase transaction” is included with every block on the Bitcoin network. A coinbase transaction is the first transaction a miner places in a block constructed by them; it is a transaction rewarding the miner in Bitcoins for successfully creating a block to be relayed to the network.
Throughout the Genesis Block Bitcoin, a message was written forever by Satoshi in history. In the coinbase transaction, with the usual block data, he added the following message :
“The Times 03/Jan/2009 Chancellor on brink of second bailout for banks”
This message is a reference to a New York Times headline, which proves that the Bitcoin Genesis Block could not have been created before that date.
This proves that there was no pre-mining before that date, assuring fairness in distribution.
There are many theories to why Satoshi used this specific headline. The most accepted one is that it is a philosophical message, referring to 2008’s economic crisis and the subsequent bank bailouts.
Why Genesis Block is needed ?
Without Genesis Block, it would be really difficult for the miners to trust a blockchain and to know when and how it started. This would be extremely impractical.
In theory, there is no real need for a Genesis Block. However, it is necessary to have a starting point that everyone can trust.
As every physical chain must begin with a single physical ring, the Genesis Block is that first, single ring. Or you could see it like the foundation of a building; it may collapse without a solid starting point. You could also view it as the starting point in a race. If every miner just started wherever they wanted, you’d have no consensus point and no basis for trust.
Genesis Block — Block data
The example taken here is the Bitcoin blockchain of the genesis block:
Number of transactions: 1
Transaction fee: $0.00
Block height: 0
Timestamp: 03/02/2009, 18:15
Block difficulty: 1
Below you will find more information on block data, which is included in Genesis Block and in all others too.
Block height of a block is the number of blocks in the chain before that given block. Therefore the height of the Genesis block is 0 because no block was placed before it.
Blocks are numbered in a blockchain order. Note that several blocks can have the same height. This could be because of a fork on the network.
The height of a blockchain is the height of the highest block. The highest block in a blockchain is the latest block. For example, at the time of writing, the current block height number of 595130.
Timestamps are generally used to store the date and time of a given event. However, it is important to note that block timestamps are not exactly accurate, and they do not need to be. Block times are accurate only to within an hour or two.
As a miner can change and fake the time of their computer, they are not trusted for chronology. They are simply a rough indicator of when the block was formed by the miner.
Position of a block in the chain does not rely on timestamps.
Nonce or “number used only once” is the number that all miners around the globe are hoping to discover in order to validate a block and receive its mining bonus. Changing the nonce causes a change in the hash. Nonce only applies to blockchains that have a Proof of Work algorithm as consensus algorithm.
Block difficulty is a number that regulates how long it can take for a miner to add a new block to the blockchain.
The difficulty is always fixed at a defined time interval, adjusted once every 2 weeks so that a block can be built at a fixed time interval. So there is a fixed time interval between constructing 2 blocks, which is approximately 10 minutes (in Bitcoin), set by the difficulty of the network.
In technical terms, difficulty is a value that is used to demonstrate, how hard is it to find a hash that will be lower than the target characterized by the system.
Nodes and Genesis Block
There are two kinds of nodes: full node and lightweight (lightnode, or simply node)
Full nodes have to follow and accept all of the blockchain’s rules. Full nodes have the entire copy of the blockchain. They get it in what we call Initial Block Download (IBD).
In the case of Bitcoin, full nodes have the Genesis Block directly written into their software, hence it is the only block they don’t need to download. They start at block 1.
They have Genesis Block in their code.
Full nodes verify the transactions validity. It requires a lot of memory and storage in order to run a full node.
The full nodes are important in maintaining security, and eventually privacy.
Any computer, which is connected to the bitcoin network is generally called a node.
It is worth mentioning that Masternodes are simply a cryptocurrency full node, but they are different in their functionality from full nodes.
Lightweight nodes do not require to download all of the copy of blockchain. They need to have only some parts that they need in order to keep operating, depending on their end user functions. They often don’t need the Genesis Block.
In order to work, lightweight nodes need to connect to full nodes. They can ask the full nodes about the information they need. In this case, the lightweight nodes need to trust that the full nodes provide valid information.
Zcoin genesis block
Although bitcoin is recognized as the leading currency in the cryptocurrency world, there are many competitors. Zcoin is one of the Altcoins that provides the most security for encrypted currency by implementing MTP protocol.
Zcoin is trying to solve Bitcoin’s security and privacy problems. Although many people think that the nature of bitcoin is anonymous and unclear around its transactions, there is no privacy mechanism for bitcoin.
But if Zcoin is successful in doing so, it will certainly be welcomed. Zcoin can also prevent Double Spending attacks, which could happen on Bitcoin network.
The Genesis block of Zcoin was launched in October 2014. 
“Times 2014/10/31 Maine Judge Says Nurse Must Follow Ebola Quarantine for Now”
Block height at this moment of writing:197889
TecraCoin genesis block
TecraCoin is a fork of privacy-focused Zcoin, using MTP protocol.
The mission of Tecra Ltd Polish-based blockchain startup is to tokenize the patents on its own blockchain which will use smart contracts, and to provide the decentralized platform bridging scientists and investors, enabling them trading Intellectual Property Rights (e.g. patents),among others.
It aims at eliminating the intermediaries, decrease the cost and speed up the process of entering the high-tech ideas to the market.
There are already 4 patents secured and the team is working on their business succeeding.
“The NY Times 2018/07/12 It Came From a Black Hole, and Landed in Antarctica”
Block height at this moment of writing:162347