A blockchain is a way of storing data so that cannot be changed anymore. This is called immutability and a very useful feature when dealing with very important data like bank records or transactions. This presentation will teach you the simplest methodology of how blockchain works.

1. Block Chain &
Cryptocurrency
Name Roll No
Waleed Ahmed 15CS188
Usama Ali Askari 15CS194
Muhammad Saqib 15CS196
Presented to:
Dr Tariq Jameel.

2. Table of contents
• What is Block chain
• How it Works?
• Blockchain P2P network.
• What is cryptocurrency?
• How it Works?
• Pros and Cons of Cryptocurrency.
• References

3. What is Blockchain?
• A blockchain is a way of storing data so that cannot be
changed anymore. This is called immutability and a very
useful feature when dealing with very important data like
bank records or transactions.
• A blockchain is a chain of blocks that contains information.
• This technique was originally described in 1991 by a group of
researchers, However it was mostly unused until it was
adapted by Satoshi Nakamoto in 2009 to create the digital
cryptocurrency Bitcoin.

9. Blockchain P2P Network
• When someone creates a new block, That new Block sends to
everyone on network.
• Each node then verifies the block to make sure that it has not been
tampered. If everything checks out, Each node adds this block to
their own blockchain.
• All the nodes in this network create consensus, They agree about
what blocks are valid and which are not. Blocks which are tempered
will be rejected by other nodes in the network.
• So to successfully tamper with a blockchain You'll need to tamper
with all blocks on the chain, redo the proof-of-work for each block
and take control of more than 50% of the peer-to-peer network.

10. New Block
New Block
New Block
New Block

11. What is Cryptocurrency?

12. What is Cryptocurrency?
• Cryptocurrency is a form of digital money that is designed to
be secure and, in many cases, anonymous. It is a currency
associated with the internet that uses cryptography, the
process of converting legible information into an almost
uncrackable code, to track purchases and transfers.
• Decentralized i.e. operates independent of any central
authority or individual.
• Transactions are irreversible.
• Virtual Currency.

13. How Cryptocurrency Works?
• Cryptocurrency is an encrypted, decentralized digital
currency transferred between peers and confirmed in a
public ledger via a process known as mining.
• Transactions are sent between peers from “cryptocurrency
wallets” by matching up public codes which relate back to
user-held private passwords (AKA cryptographic “keys”).
Transactions made between peers are recorded on a public
ledger of transactions called a “blockchain.”
• The transaction amounts are public, but who sent the
transaction is encrypted.

15. Some Cryptocurrencies are…

16. Pros and Cons of Cryptocurrency
Pros Cons
• You control your money • Cannot be recovered if lost
• Transactions cannot be
traced
• Transactions made with
cryptocurrency cannot be
traced
• Portability • No Taxation
• Virtual Currency • Can be use for Money
Laundering /Mafia

17. References
1. https://www.savjee.be/videos/simply-explained/how-does-
a-blockchain-work/
2. https://en.wikipedia.org/wiki/Satoshi_Nakamoto
3. https://en.wikipedia.org/wiki/List_of_cryptocurrencies
4. https://www.coinbase.com
5. https://coincap.io
6. https://www.binance.com