A blockchain is a growing list of records, called blocks, which are linked using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data. By design, a blockchain is resistant to modification of the data.

1. Blockchain
Presentation prepared by:
Mehul jadav

2. What is blockchain?
 There are many definition for block chain Let’s see some
important one’s:
 A mathematical structure for storing data in a way that is
nearly impossible to fake. It can be used for all kinds of
valuable data.
 A blockchain is a growing list of records, called blocks,
which are linked using cryptography
 Blockchain Is Like a Public Ledger, Information on the
blockchain is also publicly available and It’s
decentralized.

3. History of blockchain:
 The first work on a cryptographically secured chain of blocks was
described in 1991 by Stuart Haber and W. Scott Stornetta.
 The first blockchain was conceptualized by a person (or group of
people) known as Satoshi Nakamoto in 2008.
 “I’ve been working on a new electronic cash system that’s fully peer-
to-peer, with no trusted third party.” These are the words of Satoshi
Nakamoto
 (sent to a cryptography-focused mailing list in October 2008.)

4. History:
Satoshi Nakamoto Stuart HaberW. Scott Stornetta

5. It‘s based on what? Where is data stored?
Traditional Centralized system Decentralized system

6. Centralized vs Decentralized vs Distributed

7. Centralized
 Centralized systems directly control the
operation of the individual units and flow of
information from a single center.
 All individuals are directly dependent on the
central power to send and receive information,
and to be commanded.
 Single Server
 Easy to publish
 Difficult to scale
 Single point of failure

8. Distributed
 Distributed systems spread computation across
multiple nodes instead of just one.
 Google for example has adopted a distributed
architecture internally to speed up computing
and data latency.
 This means that a system can be both centralized
and distributed.

9. Decentralized
 Decentralized systems are ones where no node is
telling any other node what to do.
 The blockchain, resides on multiple computer and
decentralized because if one node goes down, the
network is still able to operate.
- Multiple Servers
- Demand and Failures better handled
( Ex. Bitcoin, Ethereum, Steemit )

10. Combination of Three technology:

11. Distributed Public Ledger
• Every single person on the network has a copy of the ledger. There is
no single centralized original copy. Ledger here means the copy of
all the transactions that ever happened.
• Blockchain is a distributed database that stores all the Bitcoin
transactions that have ever happened in the history of Bitcoin.

12. Hash Encryption
• Everything stored on the Blockchain is encrypted.
This way, everyone is able to see all the
transactions but at the same time no one will know
which of those accounts belongs to you.

13. Proof of Work
• Proof of Work is a concept invented in Bitcoin Blockchain where in the
miners (special users of Bitcoin) will validate transactions by solving
a complex mathematical puzzle called Proof of Work. Technically, there is a
hash target value designated to every block before time.

14. Is there any different type of blockchain?
 Public blockchains:
A public blockchain has absolutely no access restrictions. Anyone with
an internet connection can send transactions to it as well as become
a validator.
 Private blockchains:
A private blockchain is permissioned. One cannot join it unless
invited by the network administrators. Participant and validator access is
restricted.
 Consortium blockchains
A consortium blockchain is often said to be semi-decentralized. It,
too, is permissioned but instead of a single organization controlling it, a
number of companies might each operate a node on such a network.

15. Advantages
 Decentralized
Data is stored on Decentralized network.
 Process Integrity
Any block or even a transaction that adds to the chain cannot be
edited.
 Traceability
It can easily locate any problem and correct if there is any

16. Advantages
 Security
who enters into the Blockchain network is provided with a unique
identity which is linked to his account.
 Open Source
This Technology is Open Source
 No Central Point of Failure
any block or even a transaction that adds to the chain cannot be
edited.

17. Disadvantages:
 Power Use
The consumption of power in the Blockchain is comparatively high
 Storage Problem
Each block added to the chain increases the size of the database
 Uncertain regulatory status
In each and every part of world modern money has been created and
controlled by the central government
 Immutable
Once the smart contact is added to the blockchain, it becomes
immutable, in that it cannot be changed.

18. Where we can use this:
 Payment processing and money transfers
 Digital IDs
 Data sharing
 Copyright and royalty protection
 Digital voting
 Banking
 Real estate, land, and auto title transfers
 Immutable data backup
 Tax regulation and compliance
 Weapons tracking
 And much more…..

20. References:
 Wikipedia
 Coindesk
 Blockgeeks
 Lifehacker
 Forbes