There are three main DITA topics you will use to shape your content: concepts, references, and tasks.
A concept in DITA explains what something is. This could be anything from a software feature to a safety practice.
A reference in DITA organizes informative facts about something. This could be anything from product specifications to a list of phone numbers.
A task in DITA explains how to do something. This could be anything from configuring software to baking a cake.