> ## Documentation Index
> Fetch the complete documentation index at: https://docs.4mica.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Getting started with core concepts

> Understand what the Core Concepts section covers and choose the right reading path.

This section explains how 4Mica works beneath the SDKs and payment
middleware.

You will learn how a buyer authorizes payment, how a seller accepts it, how
collateral backs the guarantee, and how the obligation is later cleared and
settled.

You do not need to read every page in order. Start with the payment flow, then
follow the path that matches what you are building.

If you have not read the Background section, start with
[Agentic economy](/background/agentic-economy),
[Agentic payments](/background/agentic-payments), and
[Agent identity](/background/agent-identity). These pages explain why agents
need a new payment model before this section explains how 4Mica provides it.

## Begin with the payment flow

Start with [How x402 works](./how-x402-works). It introduces the HTTP 402
exchange between a buyer and seller:

1. The buyer requests a protected resource.
2. The seller returns its price and payment requirements.
3. The buyer reviews the terms and signs a guarantee.
4. The seller verifies and settles the guarantee through the facilitator.
5. Core accepts the guarantee when its signature, policy, and collateral are
   valid.

Next, read [Transaction lifecycle](./transaction-lifecycle). This explains what
happens after signing, including V1 and V2 guarantees, validation, clearing,
settlement, cancellation, disputes, and default coverage.

Read [Facilitator](./facilitator) to understand the service connecting the
seller's x402 middleware to 4Mica Core.

## Understand wallets and collateral

Read [Wallet](./wallet) to understand the relationship between an agent, wallet,
signer, spending policy, and collateral.

Then read [Deposits and withdrawals](./deposits-and-withdrawals). It explains
how a wallet deposits collateral, receives payment capacity, and later
withdraws collateral after its obligations are resolved.

[Collateral ratios](./collateral-ratios) explains why deposited collateral,
available capacity, locked exposure, and withdrawable collateral are different
amounts.

[No custodial risk](./no-custodial-risk) describes how wallet authority,
protocol contracts, Core, and Aave fit together without creating a centralized
prepaid balance.

## Understand clearing and settlement

4Mica does not require an on-chain transfer for every paid request.

[Micropayments at scale](./micro-payments-at-scale) explains why payment
authorization happens immediately while final settlement happens later.

[Bilateral netting cycles](./bilateral-netting-cycles) shows how many payable
guarantees are grouped into net debtor and creditor positions.

[Settlements](./settlements) explains how those positions are paid, claimed, or
covered by collateral when a debtor defaults.

Together, these pages explain the main scaling model:

```text theme={null}
signed guarantees
→ payable obligations
→ net positions
→ final settlement
```

## Understand security and risk

Read [Security](./security) to understand signatures, replay protection,
collateral enforcement, contracts, facilitator boundaries, and the
responsibilities of buyers and sellers.

Read [Risk management](./risk-management) for the risks that remain across
wallets, assets, collateral, validation, settlement, APIs, operations, and
external protocols.

These pages are important before using production wallets or accepting
real-value payments.

## Explore advanced concepts

After you understand the basic payment and settlement flow, continue with the
topics relevant to your product:

* [Configurable SLAs](./configurable-slas) explains how V2 guarantees can make
  payment depend on objective validation evidence.
* [Earning yield](./earning-yield) explains how configured stablecoin
  collateral can earn through Aave, including its benefits and risks.
* [Cross-chain credit](./cross-chain-credit) explains how the same payment
  pattern works across separate network-specific deployments.
* [No account setup](./no-account-setup) explains how buyers can pay new
  sellers without creating a billing account with each service.

## If you are building a buyer

A buyer is an agent or application that requests paid resources and signs
payment guarantees.

Use this reading path:

1. [How x402 works](./how-x402-works)
2. [Wallet](./wallet)
3. [Deposits and withdrawals](./deposits-and-withdrawals)
4. [Transaction lifecycle](./transaction-lifecycle)
5. [Collateral ratios](./collateral-ratios)
6. [Security](./security)
7. [Risk management](./risk-management)

Then continue to the [Buyer quick start](/buyer/quick-start) to configure
spending policy, make paid requests, test the flow, and prepare for production.

## If you are building a seller

A seller is an API, model, agent, dataset, tool, or workflow that charges for
access or completed work.

Use this reading path:

1. [How x402 works](./how-x402-works)
2. [Facilitator](./facilitator)
3. [Transaction lifecycle](./transaction-lifecycle)
4. [Micropayments at scale](./micro-payments-at-scale)
5. [Bilateral netting cycles](./bilateral-netting-cycles)
6. [Settlements](./settlements)
7. [Security](./security)

If payment depends on the quality or outcome of the work, also read
[Configurable SLAs](./configurable-slas).

Then continue to the [Seller quick start](/seller/quick-start) to protect a
route, configure pricing, verify payments, and record delivery evidence.

## If you want to understand the protocol

Use this path when evaluating 4Mica's architecture, economics, or trust model:

1. [Transaction lifecycle](./transaction-lifecycle)
2. [No custodial risk](./no-custodial-risk)
3. [Collateral ratios](./collateral-ratios)
4. [Bilateral netting cycles](./bilateral-netting-cycles)
5. [Settlements](./settlements)
6. [Earning yield](./earning-yield)
7. [Security](./security)
8. [Risk management](./risk-management)

This path explains how guarantees are backed, how obligations are reduced
through netting, how defaults are covered, and which trust assumptions remain.