Hello friends, this is my first time taking a Mini Crypto class organized by a moderator of the STEEM FOR BETTER LIFE Community which is @liasteem, I'm very enthusiastic about taking this class because the topics given are related to blockchain which is something I want to learn.

First I want to say that I am still very new to blockchain, so I will explain as best I can :)

What do you know about blockchain?

Blockchain is a word consisting of 2 different words, words are "Block" and "Chain". Block is a collection or a group and Chain is a connecting chain, so it can be concluded that Blockchain is a combination of a group that is connected by a chain and the group referred to here is computers.

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Blockchain technology is a technology that is currently being discussed because of the booming cryptocurrency called Bitcoin which uses Blockchain technology in its system. The way Blockchain works are to use the resources of computers that are connected to each other to create blocks that are linked through a chain and the goal of this is to validate the transactions created on the block.

Blockchain also uses a system called peer-to-peer. This system is a system that allows users to make transactions directly without having a third party, with this blockchain users can also avoid various frauds that can occur if there is data modification or hacking from the third party. Because this is what makes Blockchain called a decentralized system which means a system that does not require permission from anyone to run.

Describe one type of blockchain!

From what I learned from the material provided by professor @liasteem, blockchain has 4 types which include Public Blockchain, Private Blockchain, Hybrid Blockchain, and Consortium Blockchain. For this time I will explain what a Public Blockchain is.

Public Blockchain

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Public Blockchain is a type of blockchain that is very decentralized when compared to other types of blockchain. A public blockchain is a blockchain that allows anyone to register and be part of an authorized node in the blockchain network. All users will get access to all data that has been stored in the blockchain, both old data and new data.

This type of blockchain is not owned by a central authority but is regulated by users who register as nodes in the blockchain network. This user will follow an agreed protocol or better known as consensus algorithm. The first public blockchain came out with the introduction of the first cryptocurrency namely Bitcoin. BTC uses a consensus algorithm which is often called Proof of Work. The main purpose of a public blockchain is to mine and exchange cryptocurrencies such as bitcoin and Ethereum.

There are no rules or restrictions in this blockchain which makes the public blockchain known as a permissionless blockchain. Apart from being completely open and transparent it also contains no private validator nodes. Everyone has the opportunity to mine on this type of blockchain network. This type of blockchain requires downloading of all chain data so that a copy of the chain is created across all miners. And this will make the network stronger and more secure.

Explain the advantages and disadvantages of the type of blockchain you choose!

1. Advantages of Public Blockchain

• Transparency
  Transparency is the main thing that is the advantage of public blockchains because transparency is a major issue that can decide whether users want to trust a network or not. The centralized system that most systems use today makes many users hesitant to use it

  With the transparency that exists in the public blockchain, this can be a solution to this problem. Now, any person or organization can use blockchain technology to ensure users trust their system.

• High Security
  A public blockchain has enhanced security, the use of this high level of security is done to record or information stored in it. By using the blockchain public consensus method, we can ensure that users agree to the use of the information before it is used. Every transaction recorded on the node will not be lost. Thus, every transaction can be tracked, no matter how old it is. This is further enhanced by the immutability of the data stored in the network so that no data can be deleted or lost.

• No third party
  The entire transaction process on a public blockchain does not require a third party, this means that users do not have to pay additional fees for third-party activities. Thus, organizations can cut costs by using blockchain in their activities.

  Every transaction that occurs on the blockchain system can be traced from sender to receiver. In an ordering system, inventory can be difficult to track, as the vendor or customer may refuse acceptance of the product. Using the blockchain, everyone can track who is sending and who is receiving.

2. Disadvantages of Public Blockchain

• No privacy
  Since Public blockchains have a high degree of transparency, this makes this blockchain a drawback in terms of privacy. Not everyone likes it when their transactions are seen by others, so public blockchains are not suitable for people who prioritize privacy.

• Expensive cost
  Indeed, the cost of blockchain is not expensive when compared to conventional technology. But if you compare the costs between blockchains, the Public Blockchain has the most expensive level of fees. This is because the public blockchain uses a proof of work system that requires large computations that will use large electrical power. So to complete the validation process, public blockchain is still quite expensive for blockchain technology.

Visit Blockchain Demo, and what did you learn from that page? (screenshot required)

Now I will explore the website Blockchain Demo to show how the Blockchain system works.

First I will show how the Hash system works on the Blockchain, you can see the image below the data column is still empty while in the Hash column there is already a filled hash code that reads e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855.

Then I wrote "veronicataya55" in the data column, the hash code in the column below it changed to efea07343a7fa317f00418f07c1c383ea9e438143436e5f4d9a78606a544256d. This indicates that the hash will issue a different code for each different data.

Next, we will see how the Blockchain works, you can see in the picture below 5 boxes have been shown which will serve as examples of blockchain.

Then I wrote "veronicataya55" in the data column in block 1, we can see the color of the entire block is red, which means the data entered is not valid.

To validate the data I entered in block 1, then we press the "Mine" button.

After the block mining process is complete, the block will become valid and the block color will be green.

Then I do the same on the second block, but I fill the data to "veronicataya".

Then I tried to change the existing data in the first block from "veronicataya55" to "Veronicataya55", you can see in the image below because I only changed the first letter to a capital letter then the entire block that was bound became invalid.

From this, it can be concluded that any data that has been recorded in the block cannot be changed again, because the blockchain system will reject it and will invalidate the blockchain.

Then I noticed something in the column below, every hash created from the previous block will be the first hash for the block in front of it, then this continues in subsequent blocks.

Explain the advantages and disadvantages of using blockchain technology!

1. Advantages of Blockchain

• Transparency
  Blockchain has a very good level of transparency, all data recorded on the blockchain can be accessed by everyone without exception, so no one can commit fraud in terms of data on the blockchain network.

• Data Authenticity
  If data has been recorded on the Blockchain network, then the data will be on the blockchain forever and cannot be deleted or changed, this way the data on the blockchain can be ascertained its authenticity.

• High Security
  Blockchain has a very good level of security, it is very rare to add an incident where a whole blockchain is successfully hacked. This can happen because the data stored on the blockchain network is stored on nodes in all computer devices around the world, so it will be very difficult for hackers to do it.

• No third party
  The blockchain network does not require a third party in operating the system, the entire system can work independently, it only takes 2 parties who want to carry out transactions so all transactions can be carried out in full.

2. Disadvantages of Blockchain

• Must Keep Key
  The key in the blockchain wallet has a high degree of uniqueness so that the owner himself cannot memorize the wallet key. Therefore we must always keep our wallet keys multiplied and don't let them be lost or taken by someone else, if this happens then we can lose our money quickly.

• Means of Crime
  Blockchain is also often used as a transaction tool by criminals, this is because blockchain is very easy to use and everyone can get access to the blockchain without requiring any fees, so criminals will find it easy to create a large number of wallets.

• Scalability
  There are still some blockchains that still have shortcomings in terms of scalability, which means the blockchain is not able to serve a large number of transactions at the same time, this is of course a problem because the users of the blockchain are very large and spread all over the world, so we can't control it. transactions that will occur on the blockchain.

Conclusion

Blockchain is a new technology that is very good for use in various sectors, with blockchain it will make all transactions made easy, fast, and also cheaper. The loss of a third party in every transaction will take the transaction experience to a new level. I'm also very happy to see the very significant development of blockchain in these times, we should be grateful to be part of the development of a technology that will become the technology of the future.

I invite @josephwrites, @sweetgrape, and @dianarios to participate in this program.

10% payout from this post is set to @steem.education to increase activity in the community.