Goal: Understand token mechanics and why Token‑2022 exists (the “why,” not just the “what”).

Cover: Mints, ATAs, authorities, and how Token‑2022 adds programmable behavior via extensions, plus the trade‑offs.

Activity: Design a campus rewards token (paper exercise).

Takeaway: “I know how tokens differ, how Token‑2022 works conceptually, and the common pitfalls.”

1) Module overview

On Solana, a “token” isn’t an app you install — it’s state enforced by a standard program. Classic SPL Token gives you the basics (supply, balances, transfers). Token‑2022 keeps that mental model but adds a modular extensions system so you can turn on features like non‑transferability, transfer fees, allowlists via transfer hooks, interest, default‑frozen accounts, confidential transfers, and more — without writing your own custom token program.

Why this matters in a crash course: it shows how blockchains encode rules + rights (who can mint, freeze, or move funds) and how Solana exposes opt‑in, on‑chain policy at the token layer.

2) Core talking points: mint → accounts → authorities → extensions layer

Mint (the token’s root record)

• The mint address is the token’s identity (decimals, total supply).
• Authorities set policy: mint authority (create more supply), optional freeze authority (freeze/thaw accounts). Removing mint authority makes supply fixed.

Balances live in token accounts (ATAs)

• A wallet’s balance for a given mint sits in a token account; the Associated Token Account (ATA) is the standard “one per wallet + mint,” so apps and wallets can find it reliably.

What Token‑2022 changes (the big idea)

• Token‑2022 adds extensions: small, opt‑in modules stored with the mint/account that the token program enforces automatically.
• You choose the extensions at creation time (most can’t be added later) and configure parameters (for example, fee bps, hook program address).
• Think of it as a policy layer: you don’t write a custom contract to get “non‑transferable” or “charge a tiny fee” — you enable the extension and the standard program does the checking.