---
title: Key Concepts | API Docs
description: Core entities you'll work with in the Linq Partner API V2.
---

- **Chats** — Conversation threads with one or more participants.
- **Messages** — Individual messages within a chat, supporting text, attachments, and reactions.
- **Phone Numbers** — Your organization’s messaging-enabled phone numbers (iMessage, RCS, and SMS).
- **Contacts** — People in your organization’s address book.
- **Webhooks** — Real-time notifications for incoming messages, reactions, and events.