Concept, task, and reference topics are the three fundamental ways topics are categorized in DITA, each designed for specific content purposes.

Concept topics are used to explain ideas, theories, or background information to the audience. In a concept topic, you can describe the fundamental principles, definitions, and key concepts related to a particular subject matter. These topics aim to provide readers with a clear understanding of the underlying ideas before they proceed to more practical information.

Task topics are structured for presenting step-by-step procedures or instructions. They are ideal for documenting processes, workflows, or how-to guides. In a task topic, you break down a complex task into clear, actionable steps. Each step is usually accompanied by specific instructions, commands, or actions that the user needs to follow. Task topics are essential for providing users with practical guidance and ensuring they can perform tasks correctly.

Reference topics provide specific, detailed information about a subject. They are used when you need to provide in-depth information, such as specifications, parameters, properties, or technical details. Reference topics are often used to document components, functions, or attributes of a product or system. They serve as a comprehensive source of information that users can refer to when they need detailed answers or specifications.