---
url: https://talkjs.com/docs/Concepts/
title: "Concepts | TalkJS Docs"
---

For AI agents: Find a documentation index at https://talkjs.com/llms.txt (full content at https://talkjs.com/llms-full.txt). Get a markdown version of any page by appending .md to its URL path.

# Concepts

Learn the terms used throughout the platform.

| Concept | Description |
| --- | --- |
| [Conversation](https://talkjs.com/docs/Concepts/Conversations/) | A place where one or more users can write messages. A conversation has one or more participants, and zero or more ordered messages. |
| [Guest user](https://talkjs.com/docs/Concepts/Guests/) | A user with lightweight access to a conversation. Guest access is useful for conversations in which you don't require users to be `@mentioned` or to receive email or SMS notifications, for example large public group chats. Check the full overview of the [differences between participants and guest users](https://talkjs.com/docs/Features/Conversations/Group_Chat/#participants-and-guests). |
| [Message](https://talkjs.com/docs/Concepts/Messages/) | An object containing text, a file (such as an image, video, PDF, or other document), or a location share sent to a conversation. A message can be either a [user message](https://talkjs.com/docs/Concepts/Messages/) or a [system message](https://talkjs.com/docs/Concepts/System_Messages/). |
| [Message content](https://talkjs.com/docs/Concepts/Message_Content/) | The content of a message sent to a conversation, including formatting specifications. Message content can be text, files, or location shares. |
| [Participant](https://talkjs.com/docs/Concepts/Participants/) | A user who is part of a conversation. Participants can get `@mentioned`, receive notifications, and are listed in a conversation's participant list. |
| [Role](https://talkjs.com/docs/Concepts/Roles/) | A collection of settings with which you can customize both the appearance and features of the chat for a user or user group. |
| [System message](https://talkjs.com/docs/Concepts/System_Messages/) | A message sent to a conversation by the chat system or operator, instead of by a user of that conversation. |
| [Session](https://talkjs.com/docs/Concepts/Sessions/) | An active connection between a user's device and your chat, as identified by your TalkJS account. A session exists from the moment a user connects to your chat, until the moment the user navigates away from the page or closes their tab. |
| [User](https://talkjs.com/docs/Concepts/Users/) | A person or a group of people who uses your app. Each user must have a unique [user ID](https://talkjs.com/docs/Concepts/Users/#the-user-id). |
| [User ID](https://talkjs.com/docs/Concepts/Users/#id) | A unique, permanent identifier of a user of your chat. |
| [User message](https://talkjs.com/docs/Concepts/Messages/) | A message sent to a conversation by a user of that conversation. |