What is a blockchain

Understand the nature of public and permissioned blockchains and how they work

Project Source Code

Get the project source code below, and follow along with the lesson material.

Download Project Source Code

To set up the project on your local machine, please follow the directions provided in the README.md file. If you run into any issues with running the project source code, then feel free to reach out to the author in the course's Discord channel.

Lesson Transcript

  • [00:00 - 00:20] Okay, so what is a blockchain? We're going to look at the definition from Wikipedia. It says a blockchain, originally blockchain is a growing list of records called blocks that are linked together using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp and transaction data, generally represented as a mercury.

  • [00:21 - 00:47] Now that's a lot going on in there, so we're going to try to break it up. Let's see what components are there in the blockchain. First of all, a blockchain differs from normal databases that it has a peer-to-peer network. A peer-to-peer network is formed between peers who have equal privileges and share all the data between each other using a gossip protocol.

  • [00:48 - 01:35] In this kind of network, every node can talk to every other node, and nodes can drop out, and new nodes can join in without any authorization. The second component of blockchain is consensus mechanism. Having the peer-to-peer network is great, but without having a centralized server, how do these nodes come to an agreement? That is the question. The answer is consensus mechanism. A consensus mechanism is a way by which these nodes can reach an agreement. A consensus mechanism has existed before the error of the blockchain, and has been widely used in distributed systems, such as pack loss and raft. Bitcoin uses a new consensus mechanism called Proof -of-Work.

  • [01:36 - 01:59] The idea was simple. If you can prove that you have done some computation before, anyone else, you will be rewarded, and the consensus is achieved by validating the computation. We will talk about this more in the next lesson. The third component is the most important one as well, which is cryptography. Without it, the blockchain could not exist.

  • [02:00 - 02:33] Blockchain relies heavily on cryptography, such as hashes, migratories, digital signatures, public key cryptography, and more. We will walk through each of these in the cryptography module. There is a lot more that the blockchain has to offer, but to understand and improve privacy, for blockchain-based applications, you must deep dive into the fundamentals and understand the limitations of blockchain. From privacy perspective, we will be looking into several blockchains and analyzing their privacy.

  • [02:34 - 02:48] This should give you a general idea of what a blockchain is, but we will dive into the mining which creates blocks and how that works. Stay tuned!

  • [00:00 - 00:20] Okay, so what is a blockchain? We're going to look at the definition from Wikipedia. It says a blockchain, originally blockchain is a growing list of records called blocks that are linked together using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp and transaction data, generally represented as a mercury.

    [00:21 - 00:47] Now that's a lot going on in there, so we're going to try to break it up. Let's see what components are there in the blockchain. First of all, a blockchain differs from normal databases that it has a peer-to-peer network. A peer-to-peer network is formed between peers who have equal privileges and share all the data between each other using a gossip protocol.

    [00:48 - 01:35] In this kind of network, every node can talk to every other node, and nodes can drop out, and new nodes can join in without any authorization. The second component of blockchain is consensus mechanism. Having the peer-to-peer network is great, but without having a centralized server, how do these nodes come to an agreement? That is the question. The answer is consensus mechanism. A consensus mechanism is a way by which these nodes can reach an agreement. A consensus mechanism has existed before the error of the blockchain, and has been widely used in distributed systems, such as pack loss and raft. Bitcoin uses a new consensus mechanism called Proof -of-Work.

    [01:36 - 01:59] The idea was simple. If you can prove that you have done some computation before, anyone else, you will be rewarded, and the consensus is achieved by validating the computation. We will talk about this more in the next lesson. The third component is the most important one as well, which is cryptography. Without it, the blockchain could not exist.

    [02:00 - 02:33] Blockchain relies heavily on cryptography, such as hashes, migratories, digital signatures, public key cryptography, and more. We will walk through each of these in the cryptography module. There is a lot more that the blockchain has to offer, but to understand and improve privacy, for blockchain-based applications, you must deep dive into the fundamentals and understand the limitations of blockchain. From privacy perspective, we will be looking into several blockchains and analyzing their privacy.

    [02:34 - 02:48] This should give you a general idea of what a blockchain is, but we will dive into the mining which creates blocks and how that works. Stay tuned!