The large, central area of the editing window is called the canvas. This offers a preview of all visual elements in your project. The gray space around the preview is for elements that will not be present in your exported video. This is used to display off-screen elements present in scaling and panning effects. The elements displayed on the canvas reflect the position of the scrubber on the timeline.
The wide area at the bottom of the screen is the timeline. This is a visual representation of the temporal length of your screencast. The scale at the top of the timeline represents measurements of time.
The red vertical line on the timeline is called the scrubber. This represents the current temporal position of the preview currently displayed on the canvas.
The timeline is divided into tracks to manage different clips overlapping at the same time. If the clip is visual (i.e. video, image, or text), the upper most track is displayed over the lower tracks.
On the upper-right side of the editing window are the Properties tabs. These are the main editing controls of ScreenFlow and allow you to configure each clip in your screencast. It also includes the media library which stores all recorded and imported media in an unaltered state.