Polkadot Blockchain Academy, Buenos Aires 2023 - Module 3: Blockchain - Lesson 2 Blockchain Structure

This is the second lesson of the Core Blockchain Concepts module instructed by Joshy Orndorff and Andrew Burger. In this lesson we discuss hash-linked lists, block headers and bodies, and how a blockchain tracks the history of a state machine. We also dive into state roots, transaction roots, forks, and double spends.

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Context:

The second cohort of the Polkadot Blockchain Academy met in Buenos Aires in January 2023. Although the program was young at that time, the atmosphere was of learning and curiosity. While that in-person atmosphere cannot be fully captured in a video, we are now releasing these lecture recordings to give a glimpse into the PBA experience, and allow all the world to learn along with us. If you like what you see, apply to come in person at https://polkadot.academy

The content here is rough in some ways. It has matured, evolved, and developed structure in the two cohorts that have elapsed between recording and publishing. But that raw content helps to capture the spirit of these early cohorts where learners and instructors worked together to transfer knowledge as coherently and completely as possible. We invite you to learn with us now.

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Timestamps:

1:08 Shared story
1:30 Hash linked lists
6:05 Blockchain meet State Machine
7:00 States are not in blocks
8:30 State roots
11:26 What does "stored on chain" mean?
12:20 Archives, Explorers, and storing state
14:54 Forks: Alternative histories
16:31 Invalid transitions
18:48 Realistic block structure
21:25 Headers
26:58 Executing blocks
33:57 Nodes
38:28 RPC Requests are not gossiped
39:45 Incentives for RPC nodes
40:54 Transaction pool revalidation
43:44 Types of nodes
46:39 Tx Pool: More thoughts
48:29 Are transaction executed in the pool?
50:20 Intermediate states
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The Polkadot Blockchain Academy is the first of its kind — a classroom-based educational program covering the conceptual underpinnings and the hands-on application of blockchain technology, using Polkadot and Substrate as the foundations. Founded by Gavin Wood, the Academy is run by leading engineers and researchers from the Polkadot ecosystem, Parity Technologies, and the Web3 Foundation.