---
title: "XiuAI product and model API glossary"
description: "Understand subscriptions, delivered accounts, API keys, tokens, context, caching, service groups, and usage logs."
image: "https://docs.xiu.ai/og.png"
---

> XiuAI documentation index
> Full documentation index: https://docs.xiu.ai/en/llms.txt
> Check the index for current pages before reading.

# XiuAI product and model API glossary

First identify whether you are buying a subscription, receiving an account, or calling a model API. These products have different deliverables, billing, and troubleshooting paths, even when they share a model brand.

## XiuStore purchases and delivery

### AI subscription

Membership benefits for a website or application such as ChatGPT or Claude. A subscription is not API credit. Treat API credit as included only when the product page and order explicitly say so.

### Activation on your own account

The subscription is activated on an account you already use. Existing conversations and account identity usually remain, but the account must be accessible and meet the order and platform's current requirements.

### Ready-to-use account

The order delivers a new account and sign-in instructions. It does not move the subscription to your existing account. On the delivery day, check the identity, plan, term, and which security details the order permits you to change.

### One-time service

SMS verification or identity-verification assistance delivers one service, without an ongoing subscription or a guarantee of third-party approval, verification, or account status.

Before buying, read [Choose a product and delivery method](/en/store/choosing-products) and the [AI subscription buying guide](https://store.xiu.ai/en/ai-subscriptions/).

## XiuRouter model APIs

### Model API

An HTTP interface that applications use to call a model. It is separate from web memberships such as ChatGPT Plus or Claude Pro and is generally billed by actual request usage.

### API key

A credential used to call XiuRouter. It can restrict models, service groups, quota, and expiration. It is not a XiuAI sign-in token. Keep it out of repositories, screenshots, chats, and public configurations.

### Model ID

The exact model name in a request. Copy it from [Models and pricing](https://router.xiu.ai/en/pricing) or the target key's `/v1/models` response rather than constructing it from a display name.

### Token

A unit of text processing. Input and output are counted separately. Tokenization varies by model, so character counts do not convert to a fixed token count.

### Context

The input, conversation history, tool results, and reserved output a model can process together in one request. Limits depend on the model and protocol; there is no single limit shared by every XiuRouter model.

### Cache reads and writes

Some models record cache-write usage and subsequent cache-read usage separately. These dimensions are billed only when a request actually produces them. Check current rates on the pricing page and actual charges in usage logs.

### Protocol compatibility

A client's request format can connect to a gateway endpoint, such as Chat Completions, Responses, Anthropic Messages, or Gemini GenerateContent. Compatibility does not migrate every provider-hosted tool, file, feature, or cloud session.

### Service tier and service group

The pricing page uses service tiers, while API keys and usage logs use service groups. They refer to the same group value used to select a model source and price. A group name does not itself guarantee speed, quality, availability, or an SLA.

### Usage logs

Evidence of requests that have occurred. Use them to reconcile the key, model, service group, status, tokens, and cost. The pricing page describes current rates; usage logs show actual results.

Continue with [API compatibility](/en/router/api-compatibility), [models, pricing, and usage](/en/router/models-pricing-usage), and [errors and production checks](/en/router/errors-and-production).

## Sources and review date

Purchase options, protocol endpoints, pricing, and usage fields were reviewed on 2026-08-30. This translation preserves that review date. Models, prices, plans, and third-party features change; the current product page takes precedence.

Source: https://docs.xiu.ai/en/glossary/index.mdx