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# Clients & Transports

## Overview

The [Client](/docs/clients) is the composition root of Viem. It binds a [Chain](/docs/chains), a
[Transport](/docs/transports), an optional [Account](/docs/accounts), and opts into behavior
through [`.extend()`](/docs/clients/create#extending-a-client).

These guides cover Client setup, multichain resolution, and Transports that stay reliable through
provider failures, rate limits, and long-lived subscriptions.

```ts twoslash
import { Client, http, publicActions } from 'viem'
import { mainnet } from 'viem/chains'

const client = Client.create({
  chain: mainnet,
  transport: http(),
}).extend(publicActions())

const blockNumber = await client.block.getNumber()
// @log: 19868020n
```

<Cards>
  <Card icon="lucide:hammer" title="Set Up a Client" description="Compose a Chain, Transport, and Account, then tune batching, polling, and caching." to="/docs/guides/clients/setup" />

  <Card icon="lucide:route" title="Multichain Clients" description="Configure chains once and resolve a typed Client per chain on demand." to="/docs/guides/clients/multichain" />

  <Card icon="lucide:shield-check" title="Resilient Transports" description="Fail over between RPC providers and rank them by health and latency." to="/docs/guides/clients/resilient-transports" />

  <Card icon="lucide:shuffle" title="Rate Limit & Load Balance" description="Control request throughput and distribute traffic across providers." to="/docs/guides/clients/rate-limit-load-balance" />

  <Card icon="lucide:radio-tower" title="WebSocket Subscriptions" description="Use WebSocket subscriptions for blocks, pending transactions, and events." to="/docs/guides/clients/websockets" />

  <Card icon="lucide:braces" title="Custom RPC & Errors" description="Add typed RPC methods and classify provider failures." to="/docs/guides/clients/custom-rpc-errors" />
</Cards>