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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.
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.

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.
- 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.
  - How detailed should a topic be?
    A DITA topic should be as short as possible, but as long as is necessary to convey its information independently.
  - Granularity - one file per topic
    DITA topics should be saved as individual files, and the ditabase composite topic should be avoided.
  - Chunking information into topics
    Documents can be broken down into smaller chunks of content that can be treated as modular building blocks. Chunks should be organised into separate topic files.
  - Avoiding chunk structure in topics
    The hierarchy of information chunks, and the sequence that chunks should appear in published collections, should be defined in the ditamap and not through section elements or nested topics.
- 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.

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.

DITA is designed around a topic-based information architecture; topics are the building blocks of DITA documents. The topic-based approach in DITA is similar in many ways to the topic-based approach of most hypertext systems.

The DITA Architectural Specification defines a topic as follows:

A topic is a unit of information with a title and content, short enough to be specific to a single subject or answer a single question, but long enough to make sense on its own and be authored as a unit.

The DITA approach is that the author writes a topic independently of the publication in which it may eventually be published. (A publication is created by assembling topics into a hierarchical structure and publishing the collection of topics to a reading format.) This topic-oriented writing is a disciplined approach to writing that emphasises modularity and re-use of concise units of information.

A topic is created as a standalone chunk of information, typically limited to one idea. A well-written topic will fully convey that idea in one reading. Technically, a DITA topic can be as minimal as just a title, but practically that can only occur when the title alone conveys the idea completely. A topic is stored in its own file. Topics are categorised into different information types.

Although topics can technically be broken down into sections, you must take care to ensure that sections are not used as an alternative to topics. Sections should only be used where the single idea being conveyed in the topic is complex. Using sections instead of topics detracts from modularity.

Note: A number of DITA (source) topics can be later assembled into a single deliverable topic, such as an XHTML topic. DITA includes a chunk attribute for this purpose. You should not create topics in DITA according to how you want the information chunked in the deliverable reading format.