3.2 Typical Web3 architecture

You can think of Web3 architecture as a set of layers stacked on top of each other:

Layer 0 represents the underlying infrastructure that houses nodes, data storage, communication between blockchains, and consensus.
Layer 1 is the platform layer specific to a particular blockchain. Ethereum is a platform layer that enables all layers on top of it through EVM and smart contracts.
Layer 2 is the scalability layer where we can find optimistic rollups or ZK-proofs. These are solutions that scale layer 1 and enable faster transactions.
Finally, layer 3 is home to decentralized applications (OpenSea, Uniswap, MetaMask). These are applications that are based on and communicate with layer 1s. They are the frontend of the blockchain and the main way most users interact with Web3 and the underlying infrastructure.

Note: Make sure to watch the video for a guided walkthrough of the Web3 architecture in the browser.