# What an agent wallet is

Lesson 1 of [Agent wallet foundations for buyers](https://agentwalletindex.fyi/academy/agent-wallet-foundations.md), 10 minutes.

An AI agent is software that takes steps toward a goal. Some steps cost money. The agent may call a paid API, buy data or check out a cart. An agent wallet is the account or tool that lets the agent pay.

## The parts of a payment

- **Owner**: the person or company that sets the budget and carries the loss.
- **Agent**: the software that asks to pay.
- **Wallet or account**: the place that holds funds or a card and applies the rules.
- **Seller**: the service or merchant that gets paid.
- **Rail**: the payment network that moves the money. Lesson 2 covers rails.

A listing in this index describes one product or protocol. It does not describe your agent. You still decide what your agent may do.

## The five categories in this index

- **Agent wallets**: wallets an agent can use to hold and spend funds.
- **Payment protocols**: open rules that let an agent and a seller agree on a payment.
- **Card rails**: programs from card networks for agent purchases.
- **Payments platforms**: services that add accounts, rules and approvals to agent payments.
- **Key management**: layers that hold or guard the keys that sign payments.

One product can sit in more than one category. A product can be a wallet and a key layer at the same time.

## Holding money is not limiting money

A wallet does two jobs. It holds money, and it may limit how the money is spent. Not every wallet does the second job. The spend caps field on a listing shows the limits the vendor's docs describe. The value None published means the source states no cap. Read the source before you assume a limit exists.

## Why buyers need this first

An agent can pay many times a day with no person watching. A small mistake then repeats. So a buyer asks three questions first. Who holds the keys? What limits apply? Who can stop the payments? The next lessons give you the words to ask them.

## Sources

- Agent Wallet Index, How to compare agent wallets
- Agent Wallet Index, What a listing shows

Also on the [web page](https://agentwalletindex.fyi/academy/agent-wallet-foundations/what-an-agent-wallet-is).