22. Gas, L2 & Multisig
Overview
Section titled “Overview”This lesson opens the module by connecting three things a real deployment forces you to think about: gas cost and how it drives your choice of network, the role of L2s in making apps affordable, and multisig wallets as an operational safety tool. It’s the bridge from “I can deploy” to “I can deploy responsibly.”
Key concepts
Section titled “Key concepts”- Gas cost drives network choice — the same transaction that costs cents on an L2 can cost dollars on Ethereum mainnet at busy times. For most apps, where you deploy is largely a cost decision, and that’s why L2s exist for application developers.
- What an L2 is (preview) — a separate chain that executes transactions cheaply and posts data or proofs back to Ethereum for security. You get much lower fees while inheriting mainnet’s settlement guarantees. Lesson 24 explains the mechanism.
- Multisig wallets — a contract-based account that requires M-of-N signatures to act (e.g. 2 of 3). No single leaked key can move funds; several parties must agree. This is the standard way teams and DAOs custody funds and control privileged contract actions.
- Why multisig is operational, not optional — for anything holding real value or admin rights, a single EOA is a single point of failure. Multisig distributes that trust and is a baseline professional practice.
- Ties back to accounts — a multisig is a contract account (Module 1, lesson 04) with custom rules, a first concrete example of “the account is the logic,” which the account abstraction lessons (25–26) generalize.
Common pitfalls
Section titled “Common pitfalls”- Assuming mainnet is the default place to deploy. For most learning and many production apps, an L2 is the sensible choice on cost alone.
- Treating a single private key as good enough for team funds. That’s exactly the failure multisig exists to prevent.
- Confusing a multisig (a smart-contract account with M-of-N rules) with just having multiple backups of one key — they’re not the same thing.
Check yourself
Section titled “Check yourself”- For a typical app, what’s the main factor pushing you toward an L2 over mainnet?
- What does a 2-of-3 multisig protect against that a single key does not?
- Why is a multisig a contract account rather than an EOA?
Watch the Video
Section titled “Watch the Video”
Gas, L2 & Multisig
Video credit: Austin Griffith