Inundating a user with too much information at once is a common and classic user interface boo-boo. Itâ€™s best to allow users to ask for information in digestible chunks that are under their control. This is a tiny glimpse into a larger principle known as progressive disclosure in which the data presented to users is kept to the minimum and expanded as required to perform the task at hand. A good example of this might be browsing the filesystem of a computer. This information is frequently presented as a hierarchical list in which the content of folders is nested to the depth required to represent all files and folders on the system. It would be ludicrous to try to present all the files and folders on the system at once! A better approach is to allow each level in the list to be opened or closed to reveal the contained hierarchical information. Youâ€™ve surely seen such controls in any application that allows you to browse the filesystem.