Chapter · Master Ethereum
Rollups and Layer 2s
Ethereum's main chain, called Layer 1, is secure but can get slow and pricey when busy. Layer 2 networks, or rollups, fix this by handling many transactions off to the side, then posting a compressed summary back to Ethereum. You get much lower fees while still leaning on Ethereum for final security. Popular rollups include Arbitrum, Optimism, and Base. They feel like using Ethereum, just cheaper and faster.
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What this lesson covers
Same care, new address
Layer 2s make Ethereum affordable for everyday use, but they add their own quirks. You may need to bridge funds across, wait for withdrawals, and trust the rollup's own setup. Newer rollups can be less battle-tested than Ethereum itself. The scaling is real and useful, but check which network you are on and how mature it is before moving large amounts. 🐜
What you get asked
What is the main job of a Layer 2 rollup?
A rollup batches transactions off chain for low cost, then posts data back to Ethereum for security. You get speed and savings without leaving Ethereum's trust.
Ethereum's main chain is called Layer 1, while networks built on top of it for scaling are called Layer ___.
Layer 2 sits on top of Layer 1. It handles the heavy traffic and uses Ethereum underneath to keep everything secure.
Match each Layer 2 network to a quick note
Arbitrum, Optimism, and Base are all rollups that settle to Ethereum. Layer 1 is the base chain they all rely on for final security.
How did the 2024 blob upgrade, EIP-4844, help rollups?
EIP-4844, also called proto-danksharding, gave rollups a new low-cost data slot called a blob. Blobs are temporary, so they are cheaper, which pushed Layer 2 fees down further.
The rest of this chapter
Learn how Ethereum works as a programmable blockchain, from smart contracts and gas to staking, Layer 2s, and DeFi.