A topic is just a piece of work to be done. You can use topics to represent small deliverables like day-to-day tasks, big goals like "epics" or "milestones", and anything in between.
A topic has just one required property: a title. Whenever you create a topic, you'll have to provide a title.
A topic's title should be a short but meaningful description of what the work entails. Try to keep the title short so it's easy for you and your teammates to quickly read and recognize it, but at the same time ensure the title is meaningful so it's easy to understand and distinguish from other topics. It's a balancing act!
Here are some examples of great titles:
While viewing a workspace in board view, you can quickly create a topic by clicking in the empty space at the top or bottom of a column or in between topics. It's a great way to create a topic when you know exactly where in the workspace you want it!
While viewing a workspace, you can create a new topic by clicking the + button in the upper right corner. That'll bring up a dialog where you can provide the topic's title and optionally other details like labels, a description, attachments, an owner, and collaborators.
If you have a topic with a checklist containing some tasks, you can promote a task into a full-fledged topic. Hover over the task and click its ellipsis menu, then choose Promote to topic on and select the workspace and stage where the new topic should be created. The task will be converted into a child topic.
Learn more about checklists: