# Overview (/concepts)



butr is a small state machine around a pool of wallet connectors. Six ideas
explain the whole library.

1. **[Architecture](/concepts/architecture)** — the end-to-end runtime:
   discovery → adapter → store → pool → React hooks → integration. Start here
   if you want the full picture in one page.
2. **[Connectors vs. wallets](/concepts/connectors-and-wallets)** — every
   wallet is a `WalletAdapter`. butr calls the *connector* half (connect,
   getAccount, subscribe); your app calls the *wallet* half (signMessage,
   sendTx, getSigner). All adapters plug in through one seam:
   `WalletManagerConfig.createConnector`.
3. **[Platforms](/concepts/platforms)** — every connector is `evm`, `svm`,
   `sui`, or `bitcoin`. The four platforms are tracked independently, so a
   user can hold all of them at once. Chains use CAIP-2 ids (`eip155:1`,
   `solana:…`, `sui:…`, `bip122:…`).
4. **[Pool, selection, active](/concepts/pool-selection-active)** — the
   pool is every connected wallet; selection is the chosen wallet *per
   platform*; the active wallet is the single one in front of the user now.
5. **[Capabilities](/concepts/capabilities)** — flags that say what a
   wallet can do *right now*. Gate UI on these, not on method existence.
6. **[Hydration](/concepts/hydration)** — restoring the previous session
   is asynchronous because wallet adapters announce themselves asynchronously.

Two supporting topics round it out:
[persistence](/concepts/persistence) (how state survives reloads, and why
storage writes are silent) and [errors](/concepts/errors) (how thrown
values from wildly different wallet SDKs become one tagged union).