Blockchain Basics: From Blocks to Consensus

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4 lessons · Novice

Lesson 1 of 4

What Is a Blockchain?

Lesson 2 of 4

How Blocks and Chains Work

About this study

“Blockchain Basics: From Blocks to Consensus” is a free, 4-lesson study on How blockchains work at novice, created with soclever, a personal AI teacher. Each lesson takes a few minutes and ends with a check-in question; finish the curriculum and you can take a certificate test to earn a diploma. Starting is free once you sign in — or generate your own study on any topic. Shared by @jjea.

What you'll learn

What Is a Blockchain?. You just transferred money to a friend using a blockchain network. Your transaction got bundled with others into a block—a container holding a batch of records. That block was…

How Blocks and Chains Work. Most people think a blockchain is just a list of blocks stacked like files in a folder. That's wrong. Each block is mathematically locked to the one before it using cryptographic…

Consensus and Proof of Work. Thousands of computers on a Bitcoin network must agree on which transactions are real before a new block joins the chain. Without a central authority deciding this, how does the…

Trust Without a Central Authority. In 1982, computer scientist Leslie Lamport posed a puzzle: how could a group of generals coordinate an attack when some might be traitors sending false messages? He called it the…

Questions this study answers

Why does changing one old transaction in a blockchain cause a problem that spreads forward through all the blocks that come after it?

If someone changes a transaction buried in block five, why can't they simply recalculate block five's hash and update it without anyone noticing?

Why does proof of work make it economically irrational for someone to try to alter a transaction that's already been recorded in a block?

Why can't a single dishonest miner successfully rewrite old transactions in a blockchain?