The main interface. On the left is the "binder", which shows a list of all the files in the current project. In this screenshot, the corkboard is open in the top pane and text is open in the bottom pane. On the right is the inspector, which displays the synopsis, meta-data and notes pertaining to the currently viewed document.
The outliner. In this screenshot, the outliner is open in the left-hand editor pane, on the right of the binder (the blue contents list). Each document can be assigned a coloured label, and in this screenshot the rows of the outliner have been set to take on the colours of the document labels. The selected document in the outliner is open in the right-hand text pane.
Full screen mode. You can block out the rest of the screen and just edit your text against a black background, much like iPhoto's full screen mode except for writing. In this screenshot, the keywords and inspector panels are open, as is the control panel at the bottom. All of these can be hidden so that it is just you and your text.