The blockchain is a growing list of records called blocks which are linked using cryptography. So, here's a small introductory presentation to describe the basic fundamentals and data structure of the blockchain.

1. Blockchain Data Structure and Fundamentals
Satoshi nakamoto (Anonymous) was the person who invented the
blockchain in 2008 to serve as the public transaction ledger
of the cryptocurrency bitcoin.

2. What is blockchain?
Blockchain is a growing list of records called blocks which are linked using cryptography.
Where cryptography is the practice and study of technique for secure communication in the
presence of third parties called adversaries (black hat hacker ).In blockchain each block
contain cryptographic hash of the previous block. Where cryptographic hash is special class
of hash function that has certain properties use in cryptography.
In its most simple sense, the blockchain is a series of computers that each keep the same
record of an event or transaction in a ledger that is open to the public.

4. Why Blockchain?
Blockchain is decentralized computation and information sharing platform that enable
multiple authoritative domain. Blockchain technology is useful when multiple party want to
● Cooperate
● Coordinate
● Collaborate with each other.
It made for implemented bitcoin to
solve the problem of “double spending”.

5. Double-spending is a potential problem in which the same digital currency can be spent
more than once. ... It is not ideal for the same digital currency to be spendable more than
once,so in blockchain each record is encrypted, and the ledger is virtually hack-proof.

7. Properties of blockchain
● Replication : Data copied every computer that part of decentralized network, no lies
any central authority.
● Irreversible transactions : After completion of transaction no way to retrieve fund
sent.
● Accessibility : Open ( every person in blockchain get a copy of transaction and they
should read and view of recorded data)

8. ● Pseudo anonymous nature : Identity of user is not traceable by third party.
● Elliptic curve cryptography : With revealing identity network confirm transaction by
private key of admin.

10. Characteristics of blockchain
● Decentralized ledger : This make blockchain multi-organizational business network.
● Distributed ledger : It allows transactions in blockchain to have public "witnesses,"
thereby making a cyberattack more difficult.
● Safer and secure : immutability of the data. Once you have agreed on a transaction and
recorded it, it can never be changed.
● Smart contracts : The types of transactions one can carry out are agreed between
participants in advance and stored in the blockchain as “smart contracts” which helps
give confidence that everyone is playing by the rules.

11. Types of blockchain

12. ● Public Blockchain : No access restriction every participant would able to read and
write.
● Private Blockchain : It is permissioned based in which network administrators (owner)
invite to selected member, It is read by all but only owner has the right to making any
changes in rules or other terms.
● Consortium Blockchain : It is semi-decentralized system in which number of
organization controlling to it. Control of write, read and verify provided to group of
organization.

13. Data structure of Blockchain
The blockchain data structure is a back-linked list of blocks of
transactions, which is ordered.
It can be stored as a flat file or in a simple database. Each block is
identifiable by a hash, generated using the SHA 256 cryptographic
hash algorithm on the header of the block.
Each block references a previous block, also known as the parent
block, in the “previous block hash” field, in the block header.

14. Class diagram of
Blockchain

15. BLOCK HEADER The block header consists of three sets of block metadata. Metadata is
data that provides information about other data. Firstly, there is a reference to a previous
block hash, which connects this block to the previous block, lying in the blockchain.

16. Blockchain use cases area
● Banking - Avoid bank interest rate and financial crises .
● Payment and transfer - Blockchain wallet.
● Healthcare - Detail of passion access by all doctor in network .
● Law enforcement - Make Law Enforcement records immutable .

17. Blockchain use cases area
● Voting - Currently most valuable and important use case of blockchain .
● Internet of things - The blockchain can keep an immutable record of the history of
smart devices.
● Online Music - Cut Out the Middlemen fans could choose to pay for the song.
● Online gaming - Reduce Fraud and Lost Revenue more exciting and parallel gaming
universess

18. Ethereum and Solidity

19. Ethereum is open source online platform for
blockchain system which help to manage
cryptocurrency. It provide smart contract
functionality which facilitates online
contractional agreements. We implement or
setup our own digital bank using blockchain
ethereum

20. Solidity preferred default language for writing
program in blockchain. t is designed to compile to
code - for the ethereum virtual machine, it is contract
- oriented programming language for writing smart
contract which is influenced by javascript, c++, python
and powershell. Solidity basically designed to target
ethereum virtual machine.

21. Conclusion
Blockchain use mathematics to create a secure distributed ledger which enable
transaction without the need for third party.
Blockchain technology could be quite complementary in a possibility space for
the future world that includes both centralized and decentralized models. Like
any new technology, the blockchain is an idea that initially disrupts, and over time
it could promote the development of a larger ecosystem that includes both the
old way and the new innovation.

22. Github repository
Implementation of bitcoin on blockchain using c++ language Fork and clone repo
and make new change, link is provided below
https://github.com/dheerajbishnoi123/Blockchain-Implementation-c-plus-
plus.git

23. About Author
Dheeraj Poonia
I am a passionate python programmer, web developer, blockchain
lover, badminton player, graphic designer.
Currently living in Jaipur, India. My interests range from technology,
sports to music. I am also interested in competitive programming and
innovation.
https://about.me/dheerajbishnoi123