If you just want a quick answer, it is a set of boxes with captions connected with lines with ideas written over the place.
What's so useful about them? Well, they allow you to organize your thoughts pretty well. Let's say you are writing a blog post about something. You still don't know how it will unfold, but have some ideas related to it... You put the subject in the center of the page, and ideas flowing outward. This is the basis of Buzan's mind mapping system, and for this kind of setting works well. You can keep adding ideas until you can develop your writing.
Of course, you should not be restricted to one idea & branches. I think this makes for non-general mind maps, constraining our mind processes. And this is why I talk about the two best applications for iPhone and don't settle with this one. Also, I only consider those you can try for free, you should not be obliged to pay for something without knowning it will work as expected.
Then, a few days ago iMindMap, Buzan's free application (free as in if you want to export, you have to buy the Desktop version at 62€, and in 1.0 version there is no import), but it is an application I like (and use) a lot, despite these problems. It has a neat interface, and wonderful organic flowing branches, although it is focused on Buzan's mind mapping style. And it has no export options beside the Desktop version... To get the nice mind map below I took aseveral screenshots, transferred the pictures, cropped and pasted along the "seam". But is nice, isn't it? Consider buying the desktop version (although expensive, it is nice) if you like the iPhone version through this affiliate link. I ended up buying the desktop version, too.
Positioning and adding branches is genius. When you tap over a branch, a target-like drag appears. If you drag the outer blue circle, you move the branch around, if you drag the red inner circle, you add a branch and position as you like. Below you can see the process.
Selecting, moving and adding
- Exports and imports to FreeMind (Open Source multiplatform mind-mapper)
- 3D view! Look, its gorgeous
- No central idea, just put down your groups of things.