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Information types and topics
Topics are the building blocks of modular documents, and organising topics by semantic information types is one of the architectural features of DITA.
Information types
A fundamental principle of DITA is information typing, which categorises information according to the nature of the content. The three base DITA information types are concept, task and reference.
Identifying the information type
Concept, task and reference topics contain different types of content. Concept topics contain explanations, task topics contain procedural steps, and reference topics contain tabular look-up information.

Introduction
Information types and topics
Topics are the building blocks of modular documents, and organising topics by semantic information types is one of the architectural features of DITA.
- Content models and information types
  A content model is a framework that represents the structure of the information to be stored. In DITA, a content model is implemented as an information type, or topic type.
- Information types
  A fundamental principle of DITA is information typing, which categorises information according to the nature of the content. The three base DITA information types are concept, task and reference.
  - Concept
    The concept topic is one of the three base DITA information types.
  - Task
    The task topic is one of the three base DITA information types.
  - Reference
    The reference topic is one of the three base DITA information types.
  - Glossary entry
    The glossentry specialised information type was introduced to improve the glossary and terminology management.
  - Composite (ditabase)
    The composite or ditabase topic is a now obsolete tool for collecting multiple topics and nesting them within a single topic file.
  - Topic (proto information type)
    The topic information type is the ancestor of all DITA information types, and is used mainly as the basis for specialising new information types.
  - Identifying the information type
    Concept, task and reference topics contain different types of content. Concept topics contain explanations, task topics contain procedural steps, and reference topics contain tabular look-up information.
- What is a topic?
  A topic in DITA is an independent chunk of information covering a single idea or task, authored as a unit, and stored in its own file. Topics are categorised by information type. DITA's topic-based architecture enables the same topic to be used in different publications.
- Working with topics
- Specialised information types
  Specialised information types provide a topic architecture that closely matches the structure of your content.
- Topic exemplars
DITA map files
Syntax and mark-up
Language and punctuation
Graphics and figures
Cross-referencing
Cross-references are a means of binding individual topics into a coherent and navigable document.
Content re-use
Metadata, conditional processing, and indexing
The DITA documentation process
DITA authoring concepts
Moving from style-based authoring to a structured authoring methodology such as DITA requires a radically different approach to writing.

Identifying the information type

Concept, task and reference topics contain different types of content. Concept topics contain explanations, task topics contain procedural steps, and reference topics contain tabular look-up information.

An important skill of an author working in a DITA environment is typing information correctly into information types.

Of the three base DITA information types:

Concept topics are used for overviews of tasks or overviews of reference information. They tend to be short and simple.
Task topics contain procedural steps.
Reference topics detail properties and other reference (as opposed to narrative) information, typically in tabular form.

In some types of documents, an instruction may be described with a set of concept, task and reference topics. For example, the use of a car's alarm system may be covered by:

Alarm systems (concept)
Setting the alarm (task)
Alarm codes (reference)

Such a set of topics would be associated using a reltable, so that the topics would be linked or associated in the deliverable document. A typical procedure will require a concept topic and a task topic, and may require a reference topic.

While task information is generally easy to identify, it can be difficult to distinguish concept from reference information. Table 1 explains some of the characteristics of concept topics compared with reference topics.

Table 1. Characteristics of concept and reference topics
	Concept	Reference
Purpose/Function	Explanatory	Fact
Access Frequency	A few times	Repeatedly, when needed
Book Context	Front, Middle	Back
Content or Data	Content	Data