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

# What Are Skills?

> Installable packages of domain knowledge and capabilities — like apps for AI.

A skill is a package of domain knowledge and capabilities that extends what Theo can do. Think of it like an app for an AI — it gives Theo specialized expertise in a specific area.

## What's Inside a Skill

Every skill contains:

1. **System Prompt Extension** — domain instructions injected into the LLM context
2. **Tool Definitions** — callable actions the model can invoke
3. **Permissions** — what the skill needs access to
4. **Model Preference** — which model works best for this skill
5. **Trigger** — how the skill activates (keyword, event, schedule, manual)
6. **Knowledge Files** — bundled reference data

## Two Ways to Use Skills

### Installed Skills (Persistent)

Install a skill once, and it's active on every completion:

```typescript theme={null}
await theo.installSkill("skill-uuid-here");
const res = await theo.complete({ prompt: "Research the latest AI agent frameworks" });
// → Installed skill is automatically loaded
```

### Per-Request Skills (Ephemeral)

Activate skills for a single request:

```typescript theme={null}
const res = await theo.complete({
  prompt: "Check stock levels for SKU-1234",
  skills: ["inventory-check", "data-extraction"],
});
```

Both methods stack — installed skills + per-request skills are all active together.

## The Marketplace

Skills are published to the Theo marketplace. Other developers can browse, install, and rate them. Skill authors earn revenue when their skills are used.

See [Building a Skill](/skills/building-a-skill) to create your own.