This key opens up a menu that lets you perform some kind of task or customization related to what you’re currently doing. In geek-speak, it’s context sensitive, which is a fancy way of saying that the menu that appears changes according to what you’re doing on your phone when you touch the button. So if you’re looking at your contacts, for example, you’ll be able to do things like adding a contact, displaying only a certain group of contacts, backing up your contacts, and so on. If you’re looking at your calendar, you’ll be able to create a new event, change the time period that shows in your calendar, and other similar options.