According to Product Design, a concept map, or mind map is a diagram used to represent ideas linked to, and arranged radially around, a central key word or idea.
Mind mapping involves writing down a central idea and thinking up new and related ideas, which radiate out from the center. By focusing on key ideas, and then looking for branches out and connections between the ideas, you can map out your knowledge in a manner that will help reframe your knowledge.
When you take the time to concept map your topic, you're breaking your research into smaller, more manageable parts.
In my example, the Franklin Expedition was one small part of a larger effort to discover the Northwest Passage. The search for this water route started in the 1500's- and that's far too much information to include in a short research paper. An overview of the Northwest Passage will help to explain why Sir John Franklin and his crew were in the Arctic, but I need only to focus on that specific voyage.
Your concept map can also serve as a rough draft for your essay outline.