|Information types and topics|
Specialised information types provide a topic architecture that closely matches the structure of your content.
DITA is designed around topic specialisation. Many types of content will not suit the structure of the DITA base information types of concept, task and reference, but new information types, with a structure to exactly suit the nature of the content, can be evolved from the base types.
A specialised information type is always derived from another DITA information type, so that you only need to define how your information type is different from what it is based on.