One of the most annoying things that can happen when you start up you Mac is to be prompted repeatedly for a keychain password for various applications. This sometimes happens after you have changed your login password. To make matters worse the password that these applications request is the previous one and not the most recent password.
Context menus are those handy menus that pop up when you right click on Windows or control-click on a Mac. The content of these menus are specific to the area that is clicked and programs you install may modify the menu items that pop up in the context menu.