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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.
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.

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.

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.

All DITA information types have evolved from the topic proto information type. The topic type is weakly information typed, or even untyped, in that it has generic rather than semantic elements. It is designed as a starting point for specialisation, and not for use as a container for structured, semantic content.

Apart from for specialisation, the other purpose of the untyped topic information type is to store legacy information during the migration of style-based documents to DITA. For example, when migrating untyped HTML content to DITA, it can be useful to first convert HTML topics to untyped DITA topic, for later conversion to correctly typed DITA information types such as concept, task and reference.

The root element of an untyped topic is topic.